Gitlab-ci alpine image : Host key verification failed - linux

Question

In gitlab I build my job with a maven image, then copy the jar to the ssh server -> it works fine.
For a php project, I try to use alpine image. But I get rejected with 'Host key verification failed'.
The server and the key are the same.
Not working:
image: alpine:latest
stages:
- deploy
deploy:
before_script:
- apk add --update openssh-client bash
- eval $(ssh-agent -s)
- bash -c 'ssh-add <(echo "$SSH_PRIVATE_KEY")'
stage: deploy
script:
- ssh root#devsb01 "ls"
Working:
image: maven:3.6.0-jdk-10-slim
stages:
- deploy
deploy:
before_script:
- 'which ssh-agent || ( apt-get update -y && apt-get install openssh-client -y )'
- eval $(ssh-agent -s)
- ssh-add <(echo "$SSH_PRIVATE_KEY")
- '[[ -f /.dockerenv ]] && mkdir -p ~/.ssh && echo "$KNOWN_HOST" > ~/.ssh/known_hosts'
- mkdir -p ~/.ssh
- '[[ -f /.dockerenv ]] && echo -e "Host *\n\tStrictHostKeyChecking no\n\n" > ~/.ssh/config'
stage: deploy
script:
- ssh root#devsb01 "ls"
I think this has to do with the way the ssh key is add.

Answer 1

try adding theses two lines:
- mkdir ~/.ssh
- ssh-keyscan -t rsa devsb01 >> ~/.ssh/known_hosts
It works for me!
Your file will look like that:
image: alpine:latest
stages:
- deploy
deploy:
before_script:
- apk add --update openssh-client bash
- eval $(ssh-agent -s)
- bash -c 'ssh-add <(echo "$SSH_PRIVATE_KEY")'
- mkdir ~/.ssh
- ssh-keyscan -t rsa devsb01 >> ~/.ssh/known_hosts
stage: deploy
script:
- ssh root#devsb01 "ls"