Docker layering cache for maven to optimize build time

Problem statement:

For docker users, use of docker cache will save a lot of development time. Docker works based on layers and these layers are cached as per order of execution. If the docker cache is used smartly it can save a lot of time for docker users. This section only covers the advantages during the docker build as it is applicable till the docker image is created. This topic assumes fair knowledge of docker image and its usage.

Following example shows a docker file created for a spring boot application. 

Step1:- The base image is created

Step2:- Workdir is created

Step3:- Copy command is executed

Step4:- Run command is executed

Step5:- CMD command is recorded as the command for container

The actual execution happens as depicted in the diagram below. 

Step1:- An intermediate container is created which forms the Layer1 and is cached

Step2:- The earlier layer is reused and container cxGraphModel%3E%3Croot%3E%3CmxCell%20id%3D%220%22%2F%3E%3CmxCell%20id%3D%221%22%20parent%3D%220%22%2F%3E%3CmxCell%20id%3D%222%22%20value%3D%22%22%20style%3D%22shape%3Dimage%3BimageAspect%3D0%3Baspect%3Dfixed%3BverticalLabelPosition%3Dbottom%3BverticalAlign%3Dtop%3BfontSize%3D14%3Bimage%3Ddata%3Aimage%2Fpng%2CiVBORw0KGgoAAAANSUhEUgAAAekAAACgCAYAAAAo7pSHAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAAFiUAABYlAUlSJPAAACLDSURBVHhe7Z27rvy4kcb%2F%2BwAb74sMBnBHA%2Fg5JnDSoeMJB44mswC%2Fg9GBQ%2FuEHU82SUfuFzBO5o0crZZFVom3IkXq0q3u8%2F2AwjktsaniRfWRlFr69u9%2F%2F3uE9djfxz9%2B%2Bzb%2B8e%2FavtR60n4xu%2F1l%2FP23349%2FuSn73sD%2B%2Bc9%2FjgCA14POXe2cfpZBpLsNIr2F%2Ff2P38Zvv%2F%2FLeFP2vYNBpAF4TSDSL28Q6cVmZ89GnMneWKDJINIAvCYQaRjsCxhEGoDXBCINg30Bg0gD8JpApGGwL2AQaQBek8OJNDkEg8G2NwDA66Gdy8%2B0b%2F%2F5z39Gsb3YM28AAADgXYFIAwAAAAcFIg0AAAAcFIg0AKu5j8OJfv99Goc7bwIP5z6c7G%2FwT%2BcP3gLA6wORBmAt92E88UNaTq0q%2FXG26SM94Xya83gpPsYz19Fkm4qpDJTIzuZoALwHG4n053i7DOPw00%2FjT8PVfIrJ81ZO2MmS2QgHszQNjZb1UHY3XzH7g%2FSn8zB%2BRIn9CZ3Fiel4ONEfyf1jGM9TkDV2Oo3nodTGrVT62WlYmXfIgpn0o0X6%2FjEOyXnx7XQeh%2FjE2JG9RZqqDzNp8H6sE%2BlPJ84%2FkTiLPUSk2bJAG46mUwtFNzh%2BckJ%2FnLX0YF8q%2FWFVwH2USC%2FgoSJdO9%2BUgerusD8QUwBmWSXSt4uI8zBeb9fx0ivSLSepEsxo1uVmBLGgy0iaArCfINDM2gUjfzx3%2FPOZ8k7F28zgzIwDIv1IaJaXrHZMS8hr2sG18yGXjx8o0tMMM1mZuMsA%2BOFiCZEGoJV1M2kjzMPlxqJ8e5hIExJ4%2FHbOUw3qMsOWfS7t%2BUP%2B2o3uWCTwNu%2BdRZoDMh2bludtsLSzO%2BMrf86W7ZQly9PJ%2BKmJW2Gm6AYs6bKsGcgM5yBf%2FXKCq3P6bpKelk21gzGufGbw01mhztcDirSIm2J6Gbm%2BlFWeKH1BpMNB5pKS5OeK0HEelmjpkxn14%2Fp%2BRv%2FP9TPOK7TZfFv7b9t5AcCebHjj2JNFmtOVAnKUPhJI7wf9b79v80qFbGMkIJ%2BcX85kFu8%2Fex9al%2FJr10e53hMBn0QgtSSd1KEmNmUxDYJoYeCgQbM8Wz%2BrGsEd%2B7kibQJ9qX6NRekVkZY6XyekPHCj%2FsWz6bsRV3cPwJp%2B3tonU%2Brnv4ip3s9Sf4P%2BJVbNt73%2Ftp4XAOzJc0Vas%2FQEUERaAnh0YinpIsL9gUjb7faY5BMHAJt2TfBqYAqcHJTZP%2FExGlRYaIad3ujjBSAqN%2BeViVNYB4Ic12z0qSnf9PjeJ5v3lL7gQ4CfSSf%2BROQB%2F7y6AZR%2BtskNaTl5ezFSv6aPhcWXpeYofSLSk6iUKrYHk3d0Yx7Z7Ix3jo4%2BGdEi0i6PqJ9JfRT7xcJ8K%2BdQy3kBwJ68jEjnFi%2BfFoOkwPnYEzwUaRHnweyXY9u0DxLp6Jj559lgoKbj%2Bk3q0gWjeMagbXPkAW8KcqlTYd0uRp%2BVrcuzo58ZwiAeWosPev%2BTMin1q7VbINKSX02g%2B%2FwlQU3Tmz6uqPSaerDM9t28b4VMZc%2BOp%2FdrT1u%2BLf2357wAYE9eZrk7NuUa0lxgCPdHIk27XL7TSTobZDYgCMiWNFBoPtglSj2Apr66MoUDDa3OdWGMLAiIEuSyekl93wB%2Fc%2BC27XA39W7rQfF3jTjpdcP1q4mK2r7cJ6SNZwre7i%2B3vd1HM0M%2FIyRLD9NVDx190lM%2F%2F4v9rFafloX5Zv2377wAYE9e7pq0D97JKHdGKKIT1KYNBEz9XAsyG9Ar0pyetmmW%2Barmn64OHFekLWkZtmIHf%2FW64X7eK9JGSF27xKtFS8kGocx0d%2FdSwentkxMQaQBaeckbx%2BRki4KOBAz15OHjibDbPFPBCtAC6NaoIpp%2FFh98oE2upxZ9jQOa%2Fb5SN6XtGu8i0mr%2FWYleNxLs82VTac8ofVRe02dZqNe5KT5o%2BSTnRSf9fVJYKKZyjhczXpiv0n97zgsA9uQlRXr6fhJ4JGhQvtNm%2BokIj4qnk9Dm%2BZoiHd58FT6lS%2FPVBSUqp6uvMAgJk2BRnZXqg%2BkJciFLfoI1f%2FexER9esm2%2FsepuZ4820NfafwGluvFCxgcL%2BmOWPhuU6P28l5KYrp1JL%2BmTjvr57%2Bsy8GrqD1vkyxsEpf%2F2nBcA7Mk6kb5d4qeNpcaCvb1IGyTAhDtkpK1ZEIjcCVgJfFmw3IFOkZagUTK9Kl095w9tCakv7cXV2x7kPNzWZCUxkLZUrNgGUVsXylbMd5tl5JBi3RT65Mm0CW2P0mv9bvr%2BstmupVK%2FZEvroqtPzvgQlrmab%2Brsgnyz8nIecV9rPy8A2JPXFenpJErElmYq0V2s%2BU9u3Mn6WiJNRA92MP7bUT5foy9VZbi6UMbdSOTz9hYfvyfIeWZ%2FgsXf90ZlS5%2B3ntIwk16U7zKKdUNQG0nAp5%2BAkQPc%2FlH6Ur%2BTctBPpnhTN3Ym6nwUm3%2FoyDzNfTJri9jCMqsiTfWWLqsTC%2FLN2ojzyPtv23kBwJ5suNxdZs%2B8ATgCswM%2F0Ex1wAPAFwMiDUAXNIOnGWigxjRLtTOsFTNdMAGRBsADkX42P%2F%2FA%2FzDv9vntcJdZqJzh8id9jpZLe%2Bup9%2FMbA5EGwAORfiYSeN%2F177tiykfXd%2BmvCLS9zpyWf%2B%2B%2FbwpEGgAPRPpZpIH23T6%2FK1vX09rPAIC3BiINAAAAHBSINAAAAHBQINIAAADAQYFIAwAAAAcFIv2VsE9WwgM3AADgVVgv0p%2B38XoZgseBDuPlGr9iI8x7%2FslM7sEQ8SP68sfzqY93VB8RyI8q5CRC6Wcest0%2FRjN49nRg9EhF7YX5ug%2FeouN1%2BLsefowq3uwDAAAvwzqR%2FryOQ%2Fis7tAuN060VqTlGd2aJU94qglkIk6qSMvLDKK0ukhPloreapFm21pMtWdFAwAAODQrZ9K38TJcxuvNz5w%2Fp5duXMxeR5Q3C1NRLBIxmWa2RrT8xJVm1ixmYUZK3vKw%2F3RgkIu0DAbSRzuySEeiGb7yUHswPzNX1g5%2F1%2BLqC4%2BtBACAV2KXa9K3C4n0MMqq93KRllmsJi6KqBby1mbN6TZ1Zm3RRJqRmXdJ%2FBaINFH2ZSnp6kQCvzlMBh1k2huSnF9u8BC9%2FYiW%2FlekBQAAoPN8kbZCF8waQ5HmtCVxycRsqUhXj1MR6WmgUJj1FvyZ6PB3DaFg5rRfTpB8ptcuRhbn35MWAACAzg4ifRsvtNzN75ImorxZhEUQRZAmgbTCxUG8V%2BSU9H5ZWhMcSssiXD5IRaTpkE541K%2F3%2Bm8o%2BbscFuGiE2b%2FOb0Jzl9OiHzjOiPzN7eZtGkbGnrSAgAA0NlcpNNZNFEWaScgJ3oZvYigFS4n0l5IaYcCi1ws8E4YYqMX7bskQigi9ZldXaSrPioiHNHh72LmfCihfE%2FKmgtsXkc9aQEAAOhsKtI3%2FilWcGO3Jc7bBWkXvOl%2FI5D2Zqlw9syzyEaRm%2Fbz59j0a6BeXOdEo75%2Fi5l0bNtes7X%2BzQkivQ%2BZBkqZL7Hv5QEJz9YVkW5JCwAAQGcjkf7kGTQJdDCFZjSRtsuvJFI2WLtttMkF91ik89mYIxOCRBT9ndL50nH0XRHLKaOQmkiz4JRm4ok%2FGR3%2BLiK5tKDCaWz5FQt9h0gDAMBj2UCkP8frIALNmxJKIm0DOUdxO%2BOTbSJSIiBqQOd8QkFTRFHEIhWqVERK6abjaD6IuJcEp1OkibIf%2FUR1WUBWAk5D8gCVim9ZeaSdgh09aQEAAOisFGkR6KEo0ESct8yk3E9%2BplhtReE0ns8muAeiJyJiBZy30fKsm8EmYqaKooh5PNvNRaQ0K9ZEmm6A8j8rKurNApEu%2BdsP51M8uMMv1welMzP6M9dv%2BHVfZ2FFmuOsTAsAAEBnlUh%2FXsPHgSrGd3irIm0CdTTLC5ddQ0GsLcemM9iSKPL2%2BZmeCGQ4%2B5RtumUzXjlWwaLjdfjbjc1jXuilHkoWulBNm%2FjakxYAAIDOE0Sa9IODdTI7ncQ7DeL8sA0f6M2MO12eJUqiN%2BXtRUsXaYMI5OSbJtL0fG3l2eGEfL9g0fE6%2FO2Dv58OYgpEDxuxZTN1y9fHQ99U4T3pbdGTFgAAgM5GN47V2TNvoMCrD7n4r6M4sFHoSQsAAEAHIv2GuJWK%2Bg1jS4BIAwDAY4FIg3H8%2BQf%2Bhyl8FuFtSR%2BJ9Fx6AAAAKhDpr44IZsNfEl76Gwlv5W8k6HN%2FAQAAZECkvzKpQD77MwAAgIiHi%2FS%2F%2Fvf%2FYLBD2f%2F8939Z0%2FbBYDDYMw0iDfvyBpGGwWBHNYg07MsbRBoGgx3VINKwL28QaRgMdlSDSMN2sn%2BMP35Lnjj2h38o6Z5gf6Mnvf1u%2FNNv7jNEGgaDHdVWi%2FTn7Tpe%2BC1Y7lGgw3i53uzjQIWiSP%2F2j%2FFPf%2Fjd%2BF0QyL%2F7w5%2FHv3Lw9HYf%2F9qQ7tdffjft92a%2Bl6T96x%2Fcvh%2F%2FFn9%2FMhvETZqjiMpL2lFF%2Bj7%2B6Xvjy%2Fd%2FHn%2FlbRBpGAx2VFsp0rfxIuKcWvBaLFWkjRCGolsO5hxUtXTfzuNfp3QlkRbzM6d%2F%2FfZnd%2BwgUHuT4wXpYSuNBfsIIs1t%2F2MwQINIw2Cwo9pqkb5eruMtnDZ%2FXsfBCvXF7HXkIu1nWd%2BZwP1rIIa%2F%2Fu3P44%2B%2F%2BGA%2BCa8RVD8bppm1%2B34Y%2BCVtGID%2F9ZubhUseIspqWjKeRX%2F3yz3eDlthxxFp12%2FiwR1EGgaDHdV2uSZ9u9RFehLe2aAtYh4HVWcy4%2FX7isKr5qNty%2FPsNeeDm4X%2F%2BkuwWvD9uTAzV5byTdpoKT%2BY%2FcUDDuMvf6bBTpxvi%2FlViqzO0tWGVT4cRaSdH%2BkADCINg8GOapuL9OftYmfSw9VPr2ORFmFoWE6emdWmotwn0saS%2FMvfbzcR6e9Y%2FGJLy%2BxFspqWBfK7751%2Fsv9HEcs0fZfVBitb%2BXAMkQ4HUOF2iDQMBjuqbSDSn%2BM1vHHM2CUQaCIWaQ7YwdJz0VhEi6KZ7FdF9jea6bGIZCIhYkQz1w6%2FKiY%2BkNmlfLvdzJZ5ezjgmNKaY8ZL%2Bbxd%2FJVZrXyfy01GZVXL3WOSHx9Pr8c1PhxBpLmtFR8g0jAY7Ki2i0iTlWfS7WI4Kz4sFOlMWDVaQk6%2FTxaIz%2FLZqDfxIRRjZ2m5gwFClE7ZJz7Kd0Ugk8%2FFemqw6Y73X%2FhYqZit8uEAIl3xDyINg8GOajssd8uNY2ZGzRell4r0rPgk%2B1WR%2Fv539ka02rG0m9CWWnlgwcI7lbsuXM4nHjSwQE7Cz%2BVOPxfrqclkYECmDBxW%2BfB8kbb1WehzEGkYDHZU2%2BXGMbnDW2bTsUiLGDTMWlMhSCwVxLJAztgmIufsdUWa%2FbH2ZiKd%2Bp4YRBoGgx3VniDSfuZaCpqTcXDVZ0AiKl5QDi3SUpZJqHL%2FvenL3csEss2mQcHfCnX%2BwiLt2kSrZ2cQaRgMdlTbfrn788ZPIBtGuSydivQkWBTkTeAOxSD9nbQIOgX4KR09qYyXZkOhP5ZIe7%2FI3x%2FZ3%2FAYatmMQJduHOsXSCP2sz%2BP8j5Lfulna4cT6baytRwbIg2DwY5q60T6doluFgutfOOYO7AIgWphQA0EPbNktnckkVYtEwqZTSsW3ui2VCCjuivMJCVNVJcykw%2Fy7PWBP5ds%2Bt5SaykbmfWjfmkFIg2DwY5qG4v0MA7pE8gMmkiT2Vlz8rtb9dnd%2FIzvMJ12M9hhRbp285pStnR1YbFIz842ZZCgiNgkgguX3PlzyVaLdNNMmgcb6uUSbxBpGAx2VNvnmnRCSaTf0RYPFGDbGw8s5toCIg2DwY5qEOmNDSJ9HHPX%2FCtL4WwQaRgMdlSDSG9sEOnXM4g0DAY7qkGkNzaI9OsZRBoGgx3VINKwL28QaRgMdlR7uEgDAAAAoA2INAAAAHBQINIAAADAQYFIAwAAAAcFIv0oPugJXKdxuPPnrwrqAQAAmtlUpD%2Bvw%2FSIUHmXNFHM%2B%2F4xDufTePrmHxd5Og%2FjRxbA7ya2z6e7D6dpvzfzvSTtx9ntO3%2FwhhQrJCZNMUEv93E4mfxOg%2FnvK4N6AACAHrYTaX49ZbNIGyEMRTeySBw5sGvpvp3HKKUq0mLB7O0%2BuGOrYiHH23C2x8fbTPNfFdQDAAB0sZFIf45X%2B3rKy3jl2XRdpD%2FGM4vnyUTseyCG949hPA8%2Bik%2FCawTVz4ZpZu2%2BHwq6pI013s3CJQ%2Bv00pagmfRpw3XY52v8YDiK4J6AACAPjYRaVnmJmEO%2FxfSvCfhnZ1SiZhrgV1mvH5fUXjVfLRteZ7rcccpi74ZRAzxqoK%2B5B%2FmY%2FyUgQenV3PnywmSjlYHzhsOPvpAPQAAQC%2FrRZqXueX90fMi3bGcPDOrTUW5T6QNSf7l7y%2FH5Vku67QikFrmBIuTESJXlpn0sqSf2XNu2kI9AABAPytFmpe5h6v5j7fMijQLZsvNQyyiRdFM9qsie6fZFgfmLKNg5mxmW81%2BNcP5lwvgjpnMANMlfwentWYERqaY4re6IkBi9hHk7Warjxcn1AMAACxhlUg7QR5GnkRbthTp2ZltYSas2qmwhB3NtDaeXc0NMibBCcSmiCZCjuxar5SpfODHgnoAAIBFLBfpZJlbOMJMOrITXX8MZ1E501LrxsHc5jtXTlOGcJBwHrTrsATXW4uPs6L4WFAPAACwjMUiLWI8ZyTicd6yBNkwa%2BUgu%2F6a9Ax7BHOexZV8j7m7pV1emrVlzpxpF6fF9bAHqAcAAFjME0SaNJED8FzgluVKdRbGwTpY3jySSDtf8iXZeUqDmP4ZZJsw7gvqAQAAlrPyxrGc%2BeVug4gvBVATbMMQmt4sFC5FT%2BnoJzU82woD8HFEulFITD2cz7SsG4uIXo4OcZK0xk7RUv9WN0wZAeWfNOUz3ZB3rwcAANiX54i0QQKwamEADgQ9s2SGfRiRtvk1LOfXypbNPnvEycBlyq3Brzkivyuz5HevBwAA2JmniTThrj%2BGYp0%2FZ9uiPowivxnsGCLNy7QtN8YZ7ubYp%2BAarKuDvGzd4mTQ6nebh3i0zKS%2FQj0AAMC%2BbC7SGnvmfTh4VtihIe8J6gEAAFYDkd4Ydw19yY1S7wXqAQAA1gORfjY%2F%2F8D%2FMI%2F%2BfBS2LlfvZwAAOCAQ6WciQvHsv8%2Bm1c%2B9%2FwIAwMGASD%2BLVBie%2FflZbF2OtZ8BAOBAQKQBAACAgwKRBgAAAA4KRBoAAAA4KBDpN0ce8FJ%2FfCcAAIAjApF%2Ba%2BQlFe%2F0m2X%2FPO7JigOQnrQAAHA8Vor0bbzw264yG66jvGk6y1t9nrL2GEgOsuqjJdPHTgaClAXivkdUvhPPnknT8U%2BbDhAg0gCAr8OBRJotEtKFIm0EP34089cV6Wez75PHuH80CW9PWgAAOAabiDS9M7pGSaTDeEkvQXBvQgoFdoFIn87j2fyN3yEMkX4WEGkAAFjOYUSayN9itUSkh%2FHD5hMKwwqRDl4U8SFv4rL5mDzTN0HJKxcLx3GC5Qchrrz02b3f2A1S6Ptr33XM9RZaQZz6fUjSGcveXFZbKWGLB1EGftNZlK%2FxIXsjWgREGgDw3rylSN9ZLL0QrBfpU%2Fqqw%2BTVme5QfJxAiD15WaS88SsaxdbMPntFut0HN9BQLMy%2FW6Sl3jSr1QNEGgDw3mx%2FTXoYxsv1Nl2PJlpE2r5POAvKC0XafLJiUtjXhcyOjVlhCQSI%2FM8GFrw%2FmylqZebv2vRmh%2FgqQhimXU5dnPp8kLzierTvax70%2FF0%2BcwMO0z5nM3OPps0t9QCRBgC8Nwe7cczMUKMYulyk5Rguvw1EOslXPw6h%2B6yJ1SSQqXBwnpnQL6IuTn0%2BcF60UlBfh55oE%2BkCWd2m9AhvT1oAADgGK0U65%2FPzOgm3LIO3ibR2DVQXPMeMSMtnG5TXi%2FQkVql4KULihClc8tYFIpuFC6pALqUuTt0%2BmO2ysmAHVUNyPTqhWaTvxs%2FokoK3guuGHuHtSQsAAMdgc5G23C5NIi3x0t%2FZnQZzDqyLRNpgj%2BNuinqkSOvfya9Tv6RIW%2B5uiZvqlPKmdIX8m0Q6uKSgWSFrA0QaAPDe7CLSn9ehS6QJEYtYFFhc1SCfCrgmxC7Nafh4rEgnvlihUo79uiIdIm2k3SzHZS%2FsE1wa105RMrVuQyDSAID3ZmOR%2Fhw%2FzSx6sMvdwyg3fbeI9BREk4A%2BBXCT2G8WYQhFRBNpEaGTu3v5YSLtjzvQMm7kp%2BflRNrUxdn%2B3Cr2q5iHQfZlAhwgbXwO1s3DmXrBdQNEGgDw3qwTaV7Wzm0YLzdOY2gTaQNvjwJpbSmUfkfLyUxCfbYcfv%2BBIi2icD7Tfn25dzeRlnosWJhvr0gX26K0pF3wRfOhZJFvHWXrSgsAAAdkY5EexuFyHW9yWzfTLNIitOnyaHZTkfac74JIG2Sm9liRDo6r7TS8nEgb7E%2FleIbrTGuLmPw7Sr7RA1I4T75XIfKto2xdaQEA4IDsc%2BNYwp55AwAAAO8KRBoAAAA4KBDpVn7%2Bgf9hHv0ZAADAlwMi3YII5rP%2FAgAA%2BFJApOdIBfLZnwEAAHwZINIAAADAQYFIAwAAAAcFIg0AAAAcFIj0oSg8zOXLgXoAAJT4WvEBIt1B%2FvhKvZOkTxqbe%2FLYRPDYzS%2F9NKxXrQd%2BwtlcMwMAVvCk%2BNAV17VHKC8MDJuJ9OftOl4G9%2FYrZ5dRHt9dzPv%2BMQ7nU1SYk32BA%2B%2BfRkzlx1b6Z0bzCxQSO53O41B74XEHrSI9pUsac75DYQbpeNF6eBuRvo8f0WNa6bysP%2Fq1jb3yJUzeEkuWPP5XJchT%2FKX3BUQvmPExKg%2FCvE%2F1J%2Fhewd883pDRI3NL73Bv8ZfjZNWn9Dn8Sr6pD5ooZbbV%2Bfyc%2BNAV148l0p%2FjdQif390o0iagFRt1KkwgvEkBp1HMjEhPtsGJ6xop7cA50pjSeOln8Ka8iUj7cyuxlefQLvkaASIB2Sy%2FiVo8CWNAILaZaFREmoO4ewGPLja6SIul32n1t1ekw%2FKlFqR7qEg%2Fh%2BVxnev8WSJ9uzhRdi%2FWSN6sweR5%2Bw5lR9JBGe0rCgcpjEuXv0mKtp%2FMdqok2a51vrt7uYMca2UPcY0S%2BqGzvDHBS%2FMOIs1lsG%2BYk%2B5qX3Cz8hzaKV8v%2FEYAKHbYY6wX6WmWRPGJt1ns6p%2BZRfJHs4GF%2BGzLEpejLNI%2Blri4pZVf4kbUn8JBSZBvu79anBRykRYfKL2fOZMP7nhF4XmTAWvI8rjOdb6wMtaJ9OfVvTs6fC%2BlQpr31PCzTrvCnT%2Fkr2w2HYA6jc1HOlSl802jPN%2F5luD8bsiDO%2BjUeKUOK4FLMbVqtMsDYdAjpKzqSUiHpO8lI9qWfPdkj3qwuD7h2sEEIAlutM0ErnXFM4GKlm5ZZELLfea0Uxrju0kUHV9mVua7cRD2ftN3YlzA3rLd1P5BzPSrOfbK11RsUJeVGNBJ0d8ML8RxPCJKIs3bbXuW0lDVuHbPml3KGRyr3d9aHbEvaUxVY16aNqEU85ZwlPjAfszG9Qyux4WVsUqkP690DXoYr%2FoEeiLOWxq3oUNFgcsXkv63FWUrSfJp6XwtnbhMs0i30tX5pAyahT7VyqrVUWu%2BO7JLPRB8EpoTzpY7tYUnDfnggqJuabbFtGE7cF8%2FJa9kdatF%2FrNv01o9LO3nhXOIg57Le0mf2CvflFoM6GNqM9OY9by4HeiY0oZT5Qf7eIslSefiSt5m%2FSLd4m%2BtjqRPcb6pKCWU%2FTM0C1gDLxcfUrjOF%2Ba3SqTdUvdlvN4u4xBelx5om1fuOO%2BOEykQadtQ9jv0fe7QtvGkc9fzlU68pt43F2mFcsc3ne%2Bc3gTnxSJKXzq51BOnI98Hskk9SJ%2BwZvqJfMeIg9u%2BsC0laJi%2BFrpBl1YyHySt2eiTkr9J%2Bbiv0zY%2FAHWfKU1aH%2FI59sHnuyggiA%2FeKZ%2FfZAsGAHvlm9ERW2YxeU3B3gyWhpL4sSjwMW0%2FnI4f7xNc2wXlTURbUM%2BBO%2FV%2F9iva0epveE6ULBbpYleq7Z%2F77koOHR8yOL%2BFlbFCpEs3jHmTVfBNRNp%2Bz1TkYBpfvms7gnT2er7lRm3H5fEskS6gngx6XbiO2uj%2FBieZlCW10sg8ZNN6UMrcVRcRHHi17yo%2BlI%2FDvkliEbKob%2BefXfKKD4V9TW0hYmEOki7PU9B3y7kLxHSvfDPqMYDo65MmuEf%2BUhnigRmliYRYa6fIn9ZtZmvBV2u0fMvpPC3%2ByjlRM5f37DnIZVXrTjkXtuS48UEjOdc72USkB6PG%2Fp6xz%2FFml8HNPlbpbURaKi7oFFHF1%2FOV7y6sJ4vrGFs1nE6189EIL1oO9Zamd%2BUNA1%2Blo3Tk20MpyKwW6WZ%2FK2VejB5QLVkg4LSBf5lJPiJkSd%2Bu9vVCufK29%2FWZWtQWMlAI95tjSAot3yb2yjeD66USW5b2ybvtc5I%2B9DXtD%2FzZto3SV9J2ZprbzPT78izZU%2Fa3VkfSXznGqcIWUNs%2F992VHDc%2BaKw7znqRHq7mv5R4X5y3dISGk9I2dJBO%2FSwV39L5Go5ZwXWMJ4m0EuhCK6WPg7xS%2Ft58H8Q29bDHSVjpZ1lgkn5XMclHba%2F8s8u7Xq7losf50nFLM8ZF%2FX%2BvfFMqbbMRk3BOdc%2F%2Bh8eczrV83%2FT9goXiXTwHOsj9rdVR0hZpH0yo%2BpedC9tSPPbT44PGuuNscE1au3GsJtLUfq7CSo0%2FMXV2%2FpyiBS6t83G6tSev6xjPEWlfZ8koungyxAHCfl8pf3%2B%2Bj2GbetjjJCyLivgWHq5U7xlLRFrti2X%2F5pHvVgZzi86hvfJNqcSAzUiPEZ9nDpeG%2Bmi8T%2BqhYkE%2BVRFsJvW3VkdJ36m2DedT6mc7x4%2FjxgeNdcdZJdJGpd2ydjSb%2FjSb3XL3wOqd5R2MdsJlLyL6nbSt2DUiHV%2BjWdsWRxDpczANsXXFJ71WNpcX1Z%2BrG21QtCTfR7BNPexzEvpAwD6Y%2Bg2Db3g4KYft53n1e7pE2vtAZQtqwmx3x1taZvG39HtmPVsT3Pm4VE6NvfKN0WLAEsgvd%2FNRlE%2F4G%2BXJH02kpbwn9xM92Sdxr1AW16Y%2B3pXOgZwef2t1lIi0Qe1nQX%2FXYopFFUWN3jZ2lOrmCPEhZ91x1om0zJhJqFMb6k8cm05azbgw0tFL%2FUA6vesoXBEFK3amDpw%2FzxHpan0Z09vf1Un%2BMBjPsnz3Z5t62OkkDAaZoZ1MPdP2%2BHAS%2BHSb0naKdLW%2FqzcVtVLxt1SPUX2Ujr1TvlwvRVsk2PVYYn2ZMuVypccJfZd9M8IlfVvavHQO5PT4y2kbRTpug8Rqddsq0k19J%2BfQ8SFj3XFWijThZ87OBncjGe8lSnm7EU5YqfSQB3%2FNylX4GpGO81uL86e9Iy2hdmLekztj7ezM1CFtK7V%2FOBIusSTfvdmmHnY8Cel4Ijp0Mw91Mu6P%2BeHcjMb77G1KG%2FVlw6xIG2hGIzMla1wXvHs5wQyM863frGSCe9NsaId8dxFpA9dt1GamnW39RhkWRNownXu8z32uxA8RLC5r7RzIaPa3U6QJpZ%2FN3rzWKtJ0zLk2Vjh8fIh4ukjPs2fej%2BRxIl0ZmHwRUA8AgBKvFR8g0g9jW5GmEaTJKxzmmhGrbcydBwLHAvUAACjxDvEBIv0wnEhT5xBbM5KTpaXcpiXOLwHqAQBQ4kXjQ3StnQ0ivT%2FbirSBRoThNXm5tvnVQD0AAEq8YnyASAMAAADvD0QaAAAAOCgQaQAAAOCgQKQBAACAgwKRBgAAAA4KRBoAAAA4KCtEuvLcbrHCW7AAAAAAMA9EGgAAADgo%2Byx38yssi6%2BqBAAAAMAsO4i0zLDrr6oEAAAAQJ3tRTqZRRMQaQAAAKCfjUU6n0UTEGkAAACgn21FWplFExBpAAAAoJ8NRVqfRRMQaQAAAKCf7USaZ9E%2FXVKJhkgDAAAAS9hIpGUWPYzJSrcFIg0AAAD0Mo7%2FDzWYeipMGTy3AAAAAElFTkSuQmCC%3B%22%20vertex%3D%221%22%20parent%3D%221%22%3E%3CmxGeometry%20x%3D%2270%22%20y%3D%2220%22%20width%3D%22489%22%20height%3D%22160%22%20as%3D%22geometry%22%2F%3E%3C%2FmxCell%3E%3C%2Froot%3E%3C%2FmxGraphModelreated with the workdir set.

Step3:- The pom file is copied on the layer created in step2 and new layer is created as layer3

Step3:- The output from Layer3 is used to create container and src folder is copied on top

Step3:- The output from Layer4 is used to create container and maven command is executed on top of that.

Note that all the layers are cached and are available/reused next time the same dockerfile is built provided the commands and the layers don't change. 

So if the same command is executed next time, the image is built in a jiffy.

Lets run the dockerfile with the following command.

docker build -f dockerfileWithoutCache -t shried/demo:latest .

Following is the output. Its a long trace but notice the time it takes to execute 'mvn install' command. The time is significant in the overall time taken by the build. Both are marked in red in the screenshot.

And after every change in code, you will notice the same amount of time will be consumed as the downloading of dependencies happen inside the docker image which is a linux subsystem. This is worse than the build time taken on a host machine without docker. So the question is how do we leverage the docker cache to make it faster. Lets understand our maven build process first.

Solution: 

Maven Build

The maven build can be broken down in two stages here. 

1. Resolve the dependencies where the deps are downloaded from the internet/internal repositories in the m2 folder

2. Compile and package the source code into a jar

Currently the mvn install is executing both the stages in one go. If we are able to break it into two then docker can create two layers out of each stage and thus with change in source code only the compile and package layer will be recreated and we can observe later that it is quite a time saving exercise.

Lets try with the following docker file. Note the two stages of the maven build.

The actual execution happens as depicted in the diagram below. 

Step1:- An intermediate container is created which forms the Layer1 and is cached

Step2:- The earlier layer is reused and container cxGraphModel%3E%3Croot%3E%3CmxCell%20id%3D%220%22%2F%3E%3CmxCell%20id%3D%221%22%20parent%3D%220%22%2F%3E%3CmxCell%20id%3D%222%22%20value%3D%22%22%20style%3D%22shape%3Dimage%3BimageAspect%3D0%3Baspect%3Dfixed%3BverticalLabelPosition%3Dbottom%3BverticalAlign%3Dtop%3BfontSize%3D14%3Bimage%3Ddata%3Aimage%2Fpng%2CiVBORw0KGgoAAAANSUhEUgAAAekAAACgCAYAAAAo7pSHAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAAFiUAABYlAUlSJPAAACLDSURBVHhe7Z27rvy4kcb%2F%2BwAb74sMBnBHA%2Fg5JnDSoeMJB44mswC%2Fg9GBQ%2FuEHU82SUfuFzBO5o0crZZFVom3IkXq0q3u8%2F2AwjktsaniRfWRlFr69u9%2F%2F3uE9djfxz9%2B%2Bzb%2B8e%2FavtR60n4xu%2F1l%2FP23349%2FuSn73sD%2B%2Bc9%2FjgCA14POXe2cfpZBpLsNIr2F%2Ff2P38Zvv%2F%2FLeFP2vYNBpAF4TSDSL28Q6cVmZ89GnMneWKDJINIAvCYQaRjsCxhEGoDXBCINg30Bg0gD8JpApGGwL2AQaQBek8OJNDkEg8G2NwDA66Gdy8%2B0b%2F%2F5z39Gsb3YM28AAADgXYFIAwAAAAcFIg0AAAAcFIg0AKu5j8OJfv99Goc7bwIP5z6c7G%2FwT%2BcP3gLA6wORBmAt92E88UNaTq0q%2FXG26SM94Xya83gpPsYz19Fkm4qpDJTIzuZoALwHG4n053i7DOPw00%2FjT8PVfIrJ81ZO2MmS2QgHszQNjZb1UHY3XzH7g%2FSn8zB%2BRIn9CZ3Fiel4ONEfyf1jGM9TkDV2Oo3nodTGrVT62WlYmXfIgpn0o0X6%2FjEOyXnx7XQeh%2FjE2JG9RZqqDzNp8H6sE%2BlPJ84%2FkTiLPUSk2bJAG46mUwtFNzh%2BckJ%2FnLX0YF8q%2FWFVwH2USC%2FgoSJdO9%2BUgerusD8QUwBmWSXSt4uI8zBeb9fx0ivSLSepEsxo1uVmBLGgy0iaArCfINDM2gUjfzx3%2FPOZ8k7F28zgzIwDIv1IaJaXrHZMS8hr2sG18yGXjx8o0tMMM1mZuMsA%2BOFiCZEGoJV1M2kjzMPlxqJ8e5hIExJ4%2FHbOUw3qMsOWfS7t%2BUP%2B2o3uWCTwNu%2BdRZoDMh2bludtsLSzO%2BMrf86W7ZQly9PJ%2BKmJW2Gm6AYs6bKsGcgM5yBf%2FXKCq3P6bpKelk21gzGufGbw01mhztcDirSIm2J6Gbm%2BlFWeKH1BpMNB5pKS5OeK0HEelmjpkxn14%2Fp%2BRv%2FP9TPOK7TZfFv7b9t5AcCebHjj2JNFmtOVAnKUPhJI7wf9b79v80qFbGMkIJ%2BcX85kFu8%2Fex9al%2FJr10e53hMBn0QgtSSd1KEmNmUxDYJoYeCgQbM8Wz%2BrGsEd%2B7kibQJ9qX6NRekVkZY6XyekPHCj%2FsWz6bsRV3cPwJp%2B3tonU%2Brnv4ip3s9Sf4P%2BJVbNt73%2Ftp4XAOzJc0Vas%2FQEUERaAnh0YinpIsL9gUjb7faY5BMHAJt2TfBqYAqcHJTZP%2FExGlRYaIad3ujjBSAqN%2BeViVNYB4Ic12z0qSnf9PjeJ5v3lL7gQ4CfSSf%2BROQB%2F7y6AZR%2BtskNaTl5ezFSv6aPhcWXpeYofSLSk6iUKrYHk3d0Yx7Z7Ix3jo4%2BGdEi0i6PqJ9JfRT7xcJ8K%2BdQy3kBwJ68jEjnFi%2BfFoOkwPnYEzwUaRHnweyXY9u0DxLp6Jj559lgoKbj%2Bk3q0gWjeMagbXPkAW8KcqlTYd0uRp%2BVrcuzo58ZwiAeWosPev%2BTMin1q7VbINKSX02g%2B%2FwlQU3Tmz6uqPSaerDM9t28b4VMZc%2BOp%2FdrT1u%2BLf2357wAYE9eZrk7NuUa0lxgCPdHIk27XL7TSTobZDYgCMiWNFBoPtglSj2Apr66MoUDDa3OdWGMLAiIEuSyekl93wB%2Fc%2BC27XA39W7rQfF3jTjpdcP1q4mK2r7cJ6SNZwre7i%2B3vd1HM0M%2FIyRLD9NVDx190lM%2F%2F4v9rFafloX5Zv2377wAYE9e7pq0D97JKHdGKKIT1KYNBEz9XAsyG9Ar0pyetmmW%2Barmn64OHFekLWkZtmIHf%2FW64X7eK9JGSF27xKtFS8kGocx0d%2FdSwentkxMQaQBaeckbx%2BRki4KOBAz15OHjibDbPFPBCtAC6NaoIpp%2FFh98oE2upxZ9jQOa%2Fb5SN6XtGu8i0mr%2FWYleNxLs82VTac8ofVRe02dZqNe5KT5o%2BSTnRSf9fVJYKKZyjhczXpiv0n97zgsA9uQlRXr6fhJ4JGhQvtNm%2BokIj4qnk9Dm%2BZoiHd58FT6lS%2FPVBSUqp6uvMAgJk2BRnZXqg%2BkJciFLfoI1f%2FexER9esm2%2FsepuZ4820NfafwGluvFCxgcL%2BmOWPhuU6P28l5KYrp1JL%2BmTjvr57%2Bsy8GrqD1vkyxsEpf%2F2nBcA7Mk6kb5d4qeNpcaCvb1IGyTAhDtkpK1ZEIjcCVgJfFmw3IFOkZagUTK9Kl095w9tCakv7cXV2x7kPNzWZCUxkLZUrNgGUVsXylbMd5tl5JBi3RT65Mm0CW2P0mv9bvr%2BstmupVK%2FZEvroqtPzvgQlrmab%2Brsgnyz8nIecV9rPy8A2JPXFenpJErElmYq0V2s%2BU9u3Mn6WiJNRA92MP7bUT5foy9VZbi6UMbdSOTz9hYfvyfIeWZ%2FgsXf90ZlS5%2B3ntIwk16U7zKKdUNQG0nAp5%2BAkQPc%2FlH6Ur%2BTctBPpnhTN3Ym6nwUm3%2FoyDzNfTJri9jCMqsiTfWWLqsTC%2FLN2ojzyPtv23kBwJ5suNxdZs%2B8ATgCswM%2F0Ex1wAPAFwMiDUAXNIOnGWigxjRLtTOsFTNdMAGRBsADkX42P%2F%2FA%2FzDv9vntcJdZqJzh8id9jpZLe%2Bup9%2FMbA5EGwAORfiYSeN%2F177tiykfXd%2BmvCLS9zpyWf%2B%2B%2FbwpEGgAPRPpZpIH23T6%2FK1vX09rPAIC3BiINAAAAHBSINAAAAHBQINIAAADAQYFIAwAAAAcFIv2VsE9WwgM3AADgVVgv0p%2B38XoZgseBDuPlGr9iI8x7%2FslM7sEQ8SP68sfzqY93VB8RyI8q5CRC6Wcest0%2FRjN49nRg9EhF7YX5ug%2FeouN1%2BLsefowq3uwDAAAvwzqR%2FryOQ%2Fis7tAuN060VqTlGd2aJU94qglkIk6qSMvLDKK0ukhPloreapFm21pMtWdFAwAAODQrZ9K38TJcxuvNz5w%2Fp5duXMxeR5Q3C1NRLBIxmWa2RrT8xJVm1ixmYUZK3vKw%2F3RgkIu0DAbSRzuySEeiGb7yUHswPzNX1g5%2F1%2BLqC4%2BtBACAV2KXa9K3C4n0MMqq93KRllmsJi6KqBby1mbN6TZ1Zm3RRJqRmXdJ%2FBaINFH2ZSnp6kQCvzlMBh1k2huSnF9u8BC9%2FYiW%2FlekBQAAoPN8kbZCF8waQ5HmtCVxycRsqUhXj1MR6WmgUJj1FvyZ6PB3DaFg5rRfTpB8ptcuRhbn35MWAACAzg4ifRsvtNzN75ImorxZhEUQRZAmgbTCxUG8V%2BSU9H5ZWhMcSssiXD5IRaTpkE541K%2F3%2Bm8o%2BbscFuGiE2b%2FOb0Jzl9OiHzjOiPzN7eZtGkbGnrSAgAA0NlcpNNZNFEWaScgJ3oZvYigFS4n0l5IaYcCi1ws8E4YYqMX7bskQigi9ZldXaSrPioiHNHh72LmfCihfE%2FKmgtsXkc9aQEAAOhsKtI3%2FilWcGO3Jc7bBWkXvOl%2FI5D2Zqlw9syzyEaRm%2Fbz59j0a6BeXOdEo75%2Fi5l0bNtes7X%2BzQkivQ%2BZBkqZL7Hv5QEJz9YVkW5JCwAAQGcjkf7kGTQJdDCFZjSRtsuvJFI2WLtttMkF91ik89mYIxOCRBT9ndL50nH0XRHLKaOQmkiz4JRm4ok%2FGR3%2BLiK5tKDCaWz5FQt9h0gDAMBj2UCkP8frIALNmxJKIm0DOUdxO%2BOTbSJSIiBqQOd8QkFTRFHEIhWqVERK6abjaD6IuJcEp1OkibIf%2FUR1WUBWAk5D8gCVim9ZeaSdgh09aQEAAOisFGkR6KEo0ESct8yk3E9%2BplhtReE0ns8muAeiJyJiBZy30fKsm8EmYqaKooh5PNvNRaQ0K9ZEmm6A8j8rKurNApEu%2BdsP51M8uMMv1welMzP6M9dv%2BHVfZ2FFmuOsTAsAAEBnlUh%2FXsPHgSrGd3irIm0CdTTLC5ddQ0GsLcemM9iSKPL2%2BZmeCGQ4%2B5RtumUzXjlWwaLjdfjbjc1jXuilHkoWulBNm%2FjakxYAAIDOE0Sa9IODdTI7ncQ7DeL8sA0f6M2MO12eJUqiN%2BXtRUsXaYMI5OSbJtL0fG3l2eGEfL9g0fE6%2FO2Dv58OYgpEDxuxZTN1y9fHQ99U4T3pbdGTFgAAgM5GN47V2TNvoMCrD7n4r6M4sFHoSQsAAEAHIv2GuJWK%2Bg1jS4BIAwDAY4FIg3H8%2BQf%2Bhyl8FuFtSR%2BJ9Fx6AAAAKhDpr44IZsNfEl76Gwlv5W8k6HN%2FAQAAZECkvzKpQD77MwAAgIiHi%2FS%2F%2Fvf%2FYLBD2f%2F8939Z0%2FbBYDDYMw0iDfvyBpGGwWBHNYg07MsbRBoGgx3VINKwL28QaRgMdlSDSMN2sn%2BMP35Lnjj2h38o6Z5gf6Mnvf1u%2FNNv7jNEGgaDHdVWi%2FTn7Tpe%2BC1Y7lGgw3i53uzjQIWiSP%2F2j%2FFPf%2Fjd%2BF0QyL%2F7w5%2FHv3Lw9HYf%2F9qQ7tdffjft92a%2Bl6T96x%2Fcvh%2F%2FFn9%2FMhvETZqjiMpL2lFF%2Bj7%2B6Xvjy%2Fd%2FHn%2FlbRBpGAx2VFsp0rfxIuKcWvBaLFWkjRCGolsO5hxUtXTfzuNfp3QlkRbzM6d%2F%2FfZnd%2BwgUHuT4wXpYSuNBfsIIs1t%2F2MwQINIw2Cwo9pqkb5eruMtnDZ%2FXsfBCvXF7HXkIu1nWd%2BZwP1rIIa%2F%2Fu3P44%2B%2F%2BGA%2BCa8RVD8bppm1%2B34Y%2BCVtGID%2F9ZubhUseIspqWjKeRX%2F3yz3eDlthxxFp12%2FiwR1EGgaDHdV2uSZ9u9RFehLe2aAtYh4HVWcy4%2FX7isKr5qNty%2FPsNeeDm4X%2F%2BkuwWvD9uTAzV5byTdpoKT%2BY%2FcUDDuMvf6bBTpxvi%2FlViqzO0tWGVT4cRaSdH%2BkADCINg8GOapuL9OftYmfSw9VPr2ORFmFoWE6emdWmotwn0saS%2FMvfbzcR6e9Y%2FGJLy%2BxFspqWBfK7751%2Fsv9HEcs0fZfVBitb%2BXAMkQ4HUOF2iDQMBjuqbSDSn%2BM1vHHM2CUQaCIWaQ7YwdJz0VhEi6KZ7FdF9jea6bGIZCIhYkQz1w6%2FKiY%2BkNmlfLvdzJZ5ezjgmNKaY8ZL%2Bbxd%2FJVZrXyfy01GZVXL3WOSHx9Pr8c1PhxBpLmtFR8g0jAY7Ki2i0iTlWfS7WI4Kz4sFOlMWDVaQk6%2FTxaIz%2FLZqDfxIRRjZ2m5gwFClE7ZJz7Kd0Ugk8%2FFemqw6Y73X%2FhYqZit8uEAIl3xDyINg8GOajssd8uNY2ZGzRell4r0rPgk%2B1WR%2Fv539ka02rG0m9CWWnlgwcI7lbsuXM4nHjSwQE7Cz%2BVOPxfrqclkYECmDBxW%2BfB8kbb1WehzEGkYDHZU2%2BXGMbnDW2bTsUiLGDTMWlMhSCwVxLJAztgmIufsdUWa%2FbH2ZiKd%2Bp4YRBoGgx3VniDSfuZaCpqTcXDVZ0AiKl5QDi3SUpZJqHL%2FvenL3csEss2mQcHfCnX%2BwiLt2kSrZ2cQaRgMdlTbfrn788ZPIBtGuSydivQkWBTkTeAOxSD9nbQIOgX4KR09qYyXZkOhP5ZIe7%2FI3x%2FZ3%2FAYatmMQJduHOsXSCP2sz%2BP8j5Lfulna4cT6baytRwbIg2DwY5q60T6doluFgutfOOYO7AIgWphQA0EPbNktnckkVYtEwqZTSsW3ui2VCCjuivMJCVNVJcykw%2Fy7PWBP5ds%2Bt5SaykbmfWjfmkFIg2DwY5qG4v0MA7pE8gMmkiT2Vlz8rtb9dnd%2FIzvMJ12M9hhRbp285pStnR1YbFIz842ZZCgiNgkgguX3PlzyVaLdNNMmgcb6uUSbxBpGAx2VNvnmnRCSaTf0RYPFGDbGw8s5toCIg2DwY5qEOmNDSJ9HHPX%2FCtL4WwQaRgMdlSDSG9sEOnXM4g0DAY7qkGkNzaI9OsZRBoGgx3VINKwL28QaRgMdlR7uEgDAAAAoA2INAAAAHBQINIAAADAQYFIAwAAAAcFIv0oPugJXKdxuPPnrwrqAQAAmtlUpD%2Bvw%2FSIUHmXNFHM%2B%2F4xDufTePrmHxd5Og%2FjRxbA7ya2z6e7D6dpvzfzvSTtx9ntO3%2FwhhQrJCZNMUEv93E4mfxOg%2FnvK4N6AACAHrYTaX49ZbNIGyEMRTeySBw5sGvpvp3HKKUq0mLB7O0%2BuGOrYiHH23C2x8fbTPNfFdQDAAB0sZFIf45X%2B3rKy3jl2XRdpD%2FGM4vnyUTseyCG949hPA8%2Bik%2FCawTVz4ZpZu2%2BHwq6pI013s3CJQ%2Bv00pagmfRpw3XY52v8YDiK4J6AACAPjYRaVnmJmEO%2FxfSvCfhnZ1SiZhrgV1mvH5fUXjVfLRteZ7rcccpi74ZRAzxqoK%2B5B%2FmY%2FyUgQenV3PnywmSjlYHzhsOPvpAPQAAQC%2FrRZqXueX90fMi3bGcPDOrTUW5T6QNSf7l7y%2FH5Vku67QikFrmBIuTESJXlpn0sqSf2XNu2kI9AABAPytFmpe5h6v5j7fMijQLZsvNQyyiRdFM9qsie6fZFgfmLKNg5mxmW81%2BNcP5lwvgjpnMANMlfwentWYERqaY4re6IkBi9hHk7Warjxcn1AMAACxhlUg7QR5GnkRbthTp2ZltYSas2qmwhB3NtDaeXc0NMibBCcSmiCZCjuxar5SpfODHgnoAAIBFLBfpZJlbOMJMOrITXX8MZ1E501LrxsHc5jtXTlOGcJBwHrTrsATXW4uPs6L4WFAPAACwjMUiLWI8ZyTicd6yBNkwa%2BUgu%2F6a9Ax7BHOexZV8j7m7pV1emrVlzpxpF6fF9bAHqAcAAFjME0SaNJED8FzgluVKdRbGwTpY3jySSDtf8iXZeUqDmP4ZZJsw7gvqAQAAlrPyxrGc%2BeVug4gvBVATbMMQmt4sFC5FT%2BnoJzU82woD8HFEulFITD2cz7SsG4uIXo4OcZK0xk7RUv9WN0wZAeWfNOUz3ZB3rwcAANiX54i0QQKwamEADgQ9s2SGfRiRtvk1LOfXypbNPnvEycBlyq3Brzkivyuz5HevBwAA2JmniTThrj%2BGYp0%2FZ9uiPowivxnsGCLNy7QtN8YZ7ubYp%2BAarKuDvGzd4mTQ6nebh3i0zKS%2FQj0AAMC%2BbC7SGnvmfTh4VtihIe8J6gEAAFYDkd4Ydw19yY1S7wXqAQAA1gORfjY%2F%2F8D%2FMI%2F%2BfBS2LlfvZwAAOCAQ6WciQvHsv8%2Bm1c%2B9%2FwIAwMGASD%2BLVBie%2FflZbF2OtZ8BAOBAQKQBAACAgwKRBgAAAA4KRBoAAAA4KBDpN0ce8FJ%2FfCcAAIAjApF%2Ba%2BQlFe%2F0m2X%2FPO7JigOQnrQAAHA8Vor0bbzw264yG66jvGk6y1t9nrL2GEgOsuqjJdPHTgaClAXivkdUvhPPnknT8U%2BbDhAg0gCAr8OBRJotEtKFIm0EP34089cV6Wez75PHuH80CW9PWgAAOAabiDS9M7pGSaTDeEkvQXBvQgoFdoFIn87j2fyN3yEMkX4WEGkAAFjOYUSayN9itUSkh%2FHD5hMKwwqRDl4U8SFv4rL5mDzTN0HJKxcLx3GC5Qchrrz02b3f2A1S6Ptr33XM9RZaQZz6fUjSGcveXFZbKWGLB1EGftNZlK%2FxIXsjWgREGgDw3rylSN9ZLL0QrBfpU%2Fqqw%2BTVme5QfJxAiD15WaS88SsaxdbMPntFut0HN9BQLMy%2FW6Sl3jSr1QNEGgDw3mx%2FTXoYxsv1Nl2PJlpE2r5POAvKC0XafLJiUtjXhcyOjVlhCQSI%2FM8GFrw%2FmylqZebv2vRmh%2FgqQhimXU5dnPp8kLzierTvax70%2FF0%2BcwMO0z5nM3OPps0t9QCRBgC8Nwe7cczMUKMYulyk5Rguvw1EOslXPw6h%2B6yJ1SSQqXBwnpnQL6IuTn0%2BcF60UlBfh55oE%2BkCWd2m9AhvT1oAADgGK0U65%2FPzOgm3LIO3ibR2DVQXPMeMSMtnG5TXi%2FQkVql4KULihClc8tYFIpuFC6pALqUuTt0%2BmO2ysmAHVUNyPTqhWaTvxs%2FokoK3guuGHuHtSQsAAMdgc5G23C5NIi3x0t%2FZnQZzDqyLRNpgj%2BNuinqkSOvfya9Tv6RIW%2B5uiZvqlPKmdIX8m0Q6uKSgWSFrA0QaAPDe7CLSn9ehS6QJEYtYFFhc1SCfCrgmxC7Nafh4rEgnvlihUo79uiIdIm2k3SzHZS%2FsE1wa105RMrVuQyDSAID3ZmOR%2Fhw%2FzSx6sMvdwyg3fbeI9BREk4A%2BBXCT2G8WYQhFRBNpEaGTu3v5YSLtjzvQMm7kp%2BflRNrUxdn%2B3Cr2q5iHQfZlAhwgbXwO1s3DmXrBdQNEGgDw3qwTaV7Wzm0YLzdOY2gTaQNvjwJpbSmUfkfLyUxCfbYcfv%2BBIi2icD7Tfn25dzeRlnosWJhvr0gX26K0pF3wRfOhZJFvHWXrSgsAAAdkY5EexuFyHW9yWzfTLNIitOnyaHZTkfac74JIG2Sm9liRDo6r7TS8nEgb7E%2FleIbrTGuLmPw7Sr7RA1I4T75XIfKto2xdaQEA4IDsc%2BNYwp55AwAAAO8KRBoAAAA4KBDpVn7%2Bgf9hHv0ZAADAlwMi3YII5rP%2FAgAA%2BFJApOdIBfLZnwEAAHwZINIAAADAQYFIAwAAAAcFIg0AAAAcFIj0oSg8zOXLgXoAAJT4WvEBIt1B%2FvhKvZOkTxqbe%2FLYRPDYzS%2F9NKxXrQd%2BwtlcMwMAVvCk%2BNAV17VHKC8MDJuJ9OftOl4G9%2FYrZ5dRHt9dzPv%2BMQ7nU1SYk32BA%2B%2BfRkzlx1b6Z0bzCxQSO53O41B74XEHrSI9pUsac75DYQbpeNF6eBuRvo8f0WNa6bysP%2Fq1jb3yJUzeEkuWPP5XJchT%2FKX3BUQvmPExKg%2FCvE%2F1J%2Fhewd883pDRI3NL73Bv8ZfjZNWn9Dn8Sr6pD5ooZbbV%2Bfyc%2BNAV148l0p%2FjdQif390o0iagFRt1KkwgvEkBp1HMjEhPtsGJ6xop7cA50pjSeOln8Ka8iUj7cyuxlefQLvkaASIB2Sy%2FiVo8CWNAILaZaFREmoO4ewGPLja6SIul32n1t1ekw%2FKlFqR7qEg%2Fh%2BVxnev8WSJ9uzhRdi%2FWSN6sweR5%2Bw5lR9JBGe0rCgcpjEuXv0mKtp%2FMdqok2a51vrt7uYMca2UPcY0S%2BqGzvDHBS%2FMOIs1lsG%2BYk%2B5qX3Cz8hzaKV8v%2FEYAKHbYY6wX6WmWRPGJt1ns6p%2BZRfJHs4GF%2BGzLEpejLNI%2Blri4pZVf4kbUn8JBSZBvu79anBRykRYfKL2fOZMP7nhF4XmTAWvI8rjOdb6wMtaJ9OfVvTs6fC%2BlQpr31PCzTrvCnT%2Fkr2w2HYA6jc1HOlSl802jPN%2F5luD8bsiDO%2BjUeKUOK4FLMbVqtMsDYdAjpKzqSUiHpO8lI9qWfPdkj3qwuD7h2sEEIAlutM0ErnXFM4GKlm5ZZELLfea0Uxrju0kUHV9mVua7cRD2ftN3YlzA3rLd1P5BzPSrOfbK11RsUJeVGNBJ0d8ML8RxPCJKIs3bbXuW0lDVuHbPml3KGRyr3d9aHbEvaUxVY16aNqEU85ZwlPjAfszG9Qyux4WVsUqkP690DXoYr%2FoEeiLOWxq3oUNFgcsXkv63FWUrSfJp6XwtnbhMs0i30tX5pAyahT7VyqrVUWu%2BO7JLPRB8EpoTzpY7tYUnDfnggqJuabbFtGE7cF8%2FJa9kdatF%2FrNv01o9LO3nhXOIg57Le0mf2CvflFoM6GNqM9OY9by4HeiY0oZT5Qf7eIslSefiSt5m%2FSLd4m%2BtjqRPcb6pKCWU%2FTM0C1gDLxcfUrjOF%2Ba3SqTdUvdlvN4u4xBelx5om1fuOO%2BOEykQadtQ9jv0fe7QtvGkc9fzlU68pt43F2mFcsc3ne%2Bc3gTnxSJKXzq51BOnI98Hskk9SJ%2BwZvqJfMeIg9u%2BsC0laJi%2BFrpBl1YyHySt2eiTkr9J%2Bbiv0zY%2FAHWfKU1aH%2FI59sHnuyggiA%2FeKZ%2FfZAsGAHvlm9ERW2YxeU3B3gyWhpL4sSjwMW0%2FnI4f7xNc2wXlTURbUM%2BBO%2FV%2F9iva0epveE6ULBbpYleq7Z%2F77koOHR8yOL%2BFlbFCpEs3jHmTVfBNRNp%2Bz1TkYBpfvms7gnT2er7lRm3H5fEskS6gngx6XbiO2uj%2FBieZlCW10sg8ZNN6UMrcVRcRHHi17yo%2BlI%2FDvkliEbKob%2BefXfKKD4V9TW0hYmEOki7PU9B3y7kLxHSvfDPqMYDo65MmuEf%2BUhnigRmliYRYa6fIn9ZtZmvBV2u0fMvpPC3%2ByjlRM5f37DnIZVXrTjkXtuS48UEjOdc72USkB6PG%2Fp6xz%2FFml8HNPlbpbURaKi7oFFHF1%2FOV7y6sJ4vrGFs1nE6189EIL1oO9Zamd%2BUNA1%2Blo3Tk20MpyKwW6WZ%2FK2VejB5QLVkg4LSBf5lJPiJkSd%2Bu9vVCufK29%2FWZWtQWMlAI95tjSAot3yb2yjeD66USW5b2ybvtc5I%2B9DXtD%2FzZto3SV9J2ZprbzPT78izZU%2Fa3VkfSXznGqcIWUNs%2F992VHDc%2BaKw7znqRHq7mv5R4X5y3dISGk9I2dJBO%2FSwV39L5Go5ZwXWMJ4m0EuhCK6WPg7xS%2Ft58H8Q29bDHSVjpZ1lgkn5XMclHba%2F8s8u7Xq7losf50nFLM8ZF%2FX%2BvfFMqbbMRk3BOdc%2F%2Bh8eczrV83%2FT9goXiXTwHOsj9rdVR0hZpH0yo%2BpedC9tSPPbT44PGuuNscE1au3GsJtLUfq7CSo0%2FMXV2%2FpyiBS6t83G6tSev6xjPEWlfZ8koungyxAHCfl8pf3%2B%2Bj2GbetjjJCyLivgWHq5U7xlLRFrti2X%2F5pHvVgZzi86hvfJNqcSAzUiPEZ9nDpeG%2Bmi8T%2BqhYkE%2BVRFsJvW3VkdJ36m2DedT6mc7x4%2FjxgeNdcdZJdJGpd2ydjSb%2FjSb3XL3wOqd5R2MdsJlLyL6nbSt2DUiHV%2BjWdsWRxDpczANsXXFJ71WNpcX1Z%2BrG21QtCTfR7BNPexzEvpAwD6Y%2Bg2Db3g4KYft53n1e7pE2vtAZQtqwmx3x1taZvG39HtmPVsT3Pm4VE6NvfKN0WLAEsgvd%2FNRlE%2F4G%2BXJH02kpbwn9xM92Sdxr1AW16Y%2B3pXOgZwef2t1lIi0Qe1nQX%2FXYopFFUWN3jZ2lOrmCPEhZ91x1om0zJhJqFMb6k8cm05azbgw0tFL%2FUA6vesoXBEFK3amDpw%2FzxHpan0Z09vf1Un%2BMBjPsnz3Z5t62OkkDAaZoZ1MPdP2%2BHAS%2BHSb0naKdLW%2FqzcVtVLxt1SPUX2Ujr1TvlwvRVsk2PVYYn2ZMuVypccJfZd9M8IlfVvavHQO5PT4y2kbRTpug8Rqddsq0k19J%2BfQ8SFj3XFWijThZ87OBncjGe8lSnm7EU5YqfSQB3%2FNylX4GpGO81uL86e9Iy2hdmLekztj7ezM1CFtK7V%2FOBIusSTfvdmmHnY8Cel4Ijp0Mw91Mu6P%2BeHcjMb77G1KG%2FVlw6xIG2hGIzMla1wXvHs5wQyM863frGSCe9NsaId8dxFpA9dt1GamnW39RhkWRNownXu8z32uxA8RLC5r7RzIaPa3U6QJpZ%2FN3rzWKtJ0zLk2Vjh8fIh4ukjPs2fej%2BRxIl0ZmHwRUA8AgBKvFR8g0g9jW5GmEaTJKxzmmhGrbcydBwLHAvUAACjxDvEBIv0wnEhT5xBbM5KTpaXcpiXOLwHqAQBQ4kXjQ3StnQ0ivT%2FbirSBRoThNXm5tvnVQD0AAEq8YnyASAMAAADvD0QaAAAAOCgQaQAAAOCgQKQBAACAgwKRBgAAAA4KRBoAAAA4KCtEuvLcbrHCW7AAAAAAMA9EGgAAADgo%2Byx38yssi6%2BqBAAAAMAsO4i0zLDrr6oEAAAAQJ3tRTqZRRMQaQAAAKCfjUU6n0UTEGkAAACgn21FWplFExBpAAAAoJ8NRVqfRRMQaQAAAKCf7USaZ9E%2FXVKJhkgDAAAAS9hIpGUWPYzJSrcFIg0AAAD0Mo7%2FDzWYeipMGTy3AAAAAElFTkSuQmCC%3B%22%20vertex%3D%221%22%20parent%3D%221%22%3E%3CmxGeometry%20x%3D%2270%22%20y%3D%2220%22%20width%3D%22489%22%20height%3D%22160%22%20as%3D%22geometry%22%2F%3E%3C%2FmxCell%3E%3C%2Froot%3E%3C%2FmxGraphModelreated with the workdir set.

Step3:- The pom file is copied on the layer created in step2 and new layer is created as layer3

Step4:- The layer3 is used to run the command 'mvn dependency:go-offline' which resolves all the dependencies.

Step5:- The output from Layer4 is used to create container and src folder is copied on top

Step6:- The output from Layer5 is used to create container and maven command is executed on top of that.

The corresponding docker layering is as shown in the diagram below:-

The corresponding maven build screenshot looks like so.

Now at this stage change some source code(without changing the pom file) like adding classes and/or changing text and recompile the build again.

For demonstration purposes, I changed the text like so in my spring application.

Notice the use of cached layer now. Till the time there is no change in the docker commands and the layers(pom file in this case), the cache of that layer will be used for the docker build. 

Now notice the change in the timing. The build time reduced from 267.6 secs to 12.3 secs. Of course in the course of development the pom file will also change. In that case, the first instance of the build execution will take a long time. But subsequently it will start using cache again.

The cache can be cleared using the following command. Subsequent requests will download/create the layer/s again.

docker builder prune

Similar optimizations are possible for npm builds that use node.js too. Will cover that in the next article.

Last but not the least. The source code along with the images in this article are at the following location.

https://github.com/shrirange/demo

The docker image if required can be pulled from the docker hub.

docker pull shried/demo:latest

Happy coding!

About the Author:-

Shrirang Edgaonkar

The author is a software professional and an avid hobby cyclist. Likes to learn new technologies and experimenting with them. A risk taker by birth who likes to take on challenge head-on. 😀😀