Docker : failed to compute cache key - docker

Question

I am trying to build a docker image for my sample-go app.
I am running it from the sample-app folder itself and using the goland editor's terminal. But the build is failing and giving me certain errors.
My docker file looks like this:
FROM alpine:latest
RUN mkdir -p /src/build
WORKDIR /src/build
RUN apk add --no-cache tzdata ca-certificates
COPY ./configs /configs
COPY main /main
EXPOSE 8000
CMD ["/main"]
command for building:
docker build --no-cache --progress=plain - < Dockerfile
Error And Logs:
#1 [internal] load build definition from Dockerfile
#1 sha256:8bb9ee83603259cf748d90ce42602f12527fa720d7417da22799b2ad4e503497
#1 transferring dockerfile: 222B done
#1 DONE 0.0s
#2 [internal] load .dockerignore
#2 sha256:f93d938488588cd0e0a94d9d343fe69dcfd28d0cb1da95ad7aab00aac50235c3
#2 transferring context: 2B done
#2 DONE 0.0s
#3 [internal] load metadata for docker.io/library/alpine:latest
#3 sha256:13549c58a76bcb5dac9d52bc368a8fb6b5cf7659f94e3fa6294917b85546978d
#3 DONE 0.0s
#10 [1/6] FROM docker.io/library/alpine:latest
#10 sha256:d20daa00e252bfb345a1b4f53b6bb332aafe702d8de5e583a76fcd09ba7ea1c1
#10 CACHED
#7 [internal] load build context
#7 sha256:0f7a8a6082a837c139acc2855e1b745bba9f28cc96709d45cd0b7be42442c0e8
#7 transferring context: 2B done
#7 DONE 0.0s
#4 [2/6] RUN mkdir -p /src/build
#4 sha256:b9fa3007a44471d47414dd29b3ff07ead6af28ede820a2b4bae0ce84cf2c5a83
#4 CACHED
#5 [3/6] WORKDIR /src/build
#5 sha256:b2ec58a365fdd74c4f9030b0caff2e2225eea33617da306678ad037fce675388
#5 CACHED
#6 [4/6] RUN apk add --no-cache tzdata ca-certificates
#6 sha256:0966097abf956d5781bc2330d49cf715cd52c3807e8fedfff07dec50907ff03b
#6 CACHED
#9 [6/6] COPY main /main
#9 sha256:f4b81960427c014a020361bea0903728f289e1d796892fe0adc6409434f3ca76
#9 ERROR: "/main" not found: not found
#8 [5/6] COPY ./configs /configs
#8 sha256:630f272dd60dd307f40dbbdaef277ee0dfc24b71fa11e10a3b8efd64d3c05086
#8 ERROR: "/configs" not found: not found
#4 [2/6] RUN mkdir -p /src/build
#4 sha256:b9fa3007a44471d47414dd29b3ff07ead6af28ede820a2b4bae0ce84cf2c5a83
#4 DONE 0.2s
------
> [5/6] COPY ./configs /configs:
------
------
> [6/6] COPY main /main:
------
failed to compute cache key: "/main" not found: not found
PS: I am not able to find where is the problem? Help Please

Answer 1

The two folders /main and /configs does not exist.
The COPY command can't copy into this folders.
1. Solution
Create the folders on build
RUN mkdir -p /main
RUN mkdir -p /configs
And than use COPY
2. Solution
Try to build without COPY and CMD
Than run the the new image
exec into running container with bash or sh
Create the folders
Exit exec container
Create a new image of the running container with docker run commit
Stop the container and delete it
Build again with your new image and include COPY and CMD

Answer 2

This is a basic mistake.
COPY ./configs /configs: copy the folder configs from the host to the Docker image.
COPY main /main: copy the executable file main from the host to the Docker image.
The problems are:
The base Docker images do not have these folders /configs, /main. You must create them manually (Docker understood your command this way).
But I have some advice:
Create 2 Docker images for 2 purposes: build, production.
Copy the source code into Docker builder image which is use for building your app.
Copy necessary output files from the Docker builder image into the Docker production image.

Answer 3

In my case, the issue was the connected vpn/proxy network from my machine.
It worked after I disconnecting the vpn/proxy network.

Answer 4

In my case I missed the folder entry in .dockerignore file. Do something like that.
**/*
!docker-images
!configs
!main