Kaniko demo

This repo is to demonstrate how Kaniko makes use of build cache.

Build images with Docker CLI

1. Initial build:

   % docker build  -t todoapi:1  src 
   

2. Build again with cache:

   % docker build  -t todoapi:2  src 
   

3. Modify src and re-build with cache:

   % touch src/empty-3
   
   % docker build  -t todoapi:3  src 
   

Result:

Step	Time
1	3m19s
2	0m5.81s
3	0m15.85s

Build images with Kaniko

1. Set environment variable PROJECT_ID and REPO for convenience:

   % export PROJECT_ID=project_id_of_your_gcp_project
   
   % export REPO=repo_name_of_your_image
   

2. Initial build with empty cache:

   % time \
     docker run --rm  -v $(pwd)/src:/kaniko-workspace  \
     gcr.io/kaniko-project/executor:latest             \
         --cache=true  --context=/kaniko-workspace     \
         --destination=gcr.io/$PROJECT_ID/$REPO
   

3. Build again with cache:

   % time \
     docker run --rm  -v $(pwd)/src:/kaniko-workspace  \
     gcr.io/kaniko-project/executor:latest             \
         --cache=true  --context=/kaniko-workspace     \
         --destination=gcr.io/$PROJECT_ID/$REPO
   

4. Modify src and re-build with cache:

   % touch src/empty-4
   
   % time \
     docker run --rm  -v $(pwd)/src:/kaniko-workspace  \
     gcr.io/kaniko-project/executor:latest             \
         --cache=true  --context=/kaniko-workspace     \
         --destination=gcr.io/$PROJECT_ID/$REPO
   

Result:

Step	Time
2	4m23s
3	1m20s
4	1m55s

Caveat with Kaniko + .NET Core SDK

If you use dotnet/core/sdk as base image, you may encounter error messages near the end of Kaniko build steps, similar to the following:

error building image: error building stage: Unable to add file /tmp/clr-debug-pipe-149-16587078-out to layered map: Error creating hash for /tmp/clr-debug-pipe-149-16587078-out: lstat /tmp/clr-debug-pipe-149-16587078-out: no such file or directory

A workaround is to set environment variable COMPlus_EnableDiagnostics before dotnet publish in Dockerfile:

ENV COMPlus_EnableDiagnostics=0
...
dotnet publish

For more info, see GoogleContainerTools/kaniko#391 (comment)

About the TodoApi source code

The sample code in src directory was extracted from the TodoApi demo in the Microsoft Docs site, retrieved on Nov 27, 2019:

• Document - Tutorial: Create a web API with ASP.NET Core MVC

• Source code - https://github.com/aspnet/AspNetCore.Docs/tree/master/aspnetcore/tutorials/first-web-api/samples/3.0/TodoApi

The original source code to be used in this repo is packed in the TodoApi-original.zip file for your reference.