Dockerfile alpine image apk cannot find Java 8

Question

I wanted to reduce my docker image and switched to an alpine base image instead. This lead to problems bash not finding apt. Turns out, I have to use apk instead. However, it does not seem to find the java version I need. Here is my dockerfile

#Use alpine golang
FROM golang:alpine

#Get the code from local code commit repo
WORKDIR /go/src/xxx
COPY . /go/src/xxx

#Install Java and cleanup after in the same layer
RUN apk update && apk add openjdk-8-jre-headless && rm -rf /var/lib/apt/lists/*

#Install dependencies recursively and remove the third_party directory after it has been used for compiling.
RUN go get ./... && go run setup.go && RUN rm -rf third_party
#More commands...



 ---> 32a6b6b5f196 
Step 4/8 : RUN apk update && apk add openjdk-8-jre-headless && rm -rf /var/lib/apt/lists/* 
 ---> Running in bc48930e48be 
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/main/x86_64/APKINDEX.tar.gz 
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/community/x86_64/APKINDEX.tar.gz 
v3.9.4-4-gd5dd5c1cd0 [http://dl-cdn.alpinelinux.org/alpine/v3.9/main] 
v3.9.4-5-gcfdf5452f1 [http://dl-cdn.alpinelinux.org/alpine/v3.9/community] 
OK: 9766 distinct packages available 
  openjdk-8-jre-headless (missing): 
·[91mERROR: unsatisfiable constraints: 
·[0m    required by: world[openjdk-8-jre-headless] 
The command '/bin/sh -c apk update && apk add openjdk-8-jre-headless && rm -rf /var/lib/apt/lists/*' returned a non-zero code: 1

I have also tried

RUN apk update && apk add -t jessie-backports openjdk-8-jre-headless ca-certificates-java && rm -rf /var/lib/apt/lists/*

According to https://unix.stackexchange.com/questions/342403/openjdk-8-jre-headless-depends-ca-certificates-java-but-it-is-not-going-to-be but that also fails, not sure if the -t flags fault:

Step 4/7 : RUN apk update && apk add -t jessie-backports openjdk-8-jre-headless ca-certificates-java && rm -rf /var/lib/apt/lists/* 
 ---> Running in 1e2ef22e7c16 
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/main/x86_64/APKINDEX.tar.gz 
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/community/x86_64/APKINDEX.tar.gz 
v3.9.4-4-gd5dd5c1cd0 [http://dl-cdn.alpinelinux.org/alpine/v3.9/main] 
v3.9.4-5-gcfdf5452f1 [http://dl-cdn.alpinelinux.org/alpine/v3.9/community] 
OK: 9766 distinct packages available 
·[91mERROR: unsatisfiable constraints: 
·[0m  openjdk-8-jre-headless (missing): 
    required by: jessie-backports-0[openjdk-8-jre-headless] 
  ca-certificates-java (missing): 
    required by: jessie-backports-0[ca-certificates-java] 
The command '/bin/sh -c apk update && apk add -t jessie-backports openjdk-8-jre-headless ca-certificates-java && rm -rf /var/lib/apt/lists/*' returned a non-zero code: 3 

Answer 1

Alpine uses entirely different package repositories than Debian or Ubuntu. The package openjdk-8-jre-headless doesn't exist there. You can check this here and find the correct package that fits your needs.