Error job failed exit code 127

I’m trying to create a CI/CD Pipeline for a simple java/maven project.
The runner that I’m using is a docker runner.
I’m using a dockerfile to create a container which installs maven/java/etc.. and in this container the program should be tested.

Sorry for the question but I am new to CI/CD Pipelines in GitLab.

GitHub works just fine have a look: https://github.com/ni920/CICD-Test

Thank you

Here are the CI logs

...
Executing "step_script" stage of the job script
 $ docker build --build-arg JAVA_VERSION=openjdk7
 /bin/sh: eval: line 95: docker: not found
Cleaning up file based variables
 ERROR: Job failed: exit code 127

Thats the .gitlab-ci.yml

stages:
  - java7
# - java11
# - deploy


java7:
  stage: java7
  script:
      - docker build --build-arg JAVA_VERSION=openjdk7
 # tags:
 #   - docker

#java11:
#  stage: java11
#  script:
#    - docker build --build-arg JAVA_VERSION=openjdk11
#  tags:
#    - docker

Thats the dockerfile

# Pull base image.
FROM alpine as build

ARG MAVEN_VERSION=3.6.1
ARG USER_HOME_DIR="/root"
ARG JAVA_VERSION=openjdk7
ARG BASE_URL=https://apache.osuosl.org/maven/maven-3/${MAVEN_VERSION}/binaries

ENV HTTP_PROXY=#comment
ENV HTTPS_PROXY=#comment

# Install Java.
RUN apk --update --no-cache add JAVA_VERSION curl

RUN mkdir -p /usr/share/maven /usr/share/maven/ref 
 && curl -fsSL -o /tmp/apache-maven.tar.gz ${BASE_URL}/apache-maven-${MAVEN_VERSION}-bin.tar.gz 
 && tar -xzf /tmp/apache-maven.tar.gz -C /usr/share/maven --strip-components=1 
 && rm -f /tmp/apache-maven.tar.gz 
 && ln -s /usr/share/maven/bin/mvn /usr/bin/mvn

ENV MAVEN_HOME /usr/share/maven
ENV MAVEN_CONFIG "$USER_HOME_DIR/.m2"

# Define working directory.
WORKDIR /data

# Define commonly used JAVA_HOME variable
ENV JAVA_HOME /usr/lib/jvm/default-jvm/

# Define default command.
CMD ["mvn", "--version"]

Job for test.service failed because the control process exited with error code.
See "systemctl status test.service" and "journalctl -xe" for details.

Jul 04 12:23:03 spider systemd[1]: Starting Мой тестовый сервис...
Jul 04 12:23:03 spider systemd[1]: test.service: Control process exited, code=exited status=127
Jul 04 12:23:03 spider systemd[1]: Failed to start Мой тестовый сервис.
Jul 04 12:23:03 spider systemd[1]: test.service: Unit entered failed state.
Jul 04 12:23:03 spider systemd[1]: test.service: Failed with result 'exit-code'.

[Unit]
Description=Мой тестовый сервис
After=network.target

[Service]
Type=simple
User=spider
Group=spider
WorkingDirectory=/home/spider/src/test
ExecStartPre=/bin/echo "OPTS=$OPTS_COMMON">/tmp/run.log
ExecStart=/usr/bin/node test.js >/tmp/run.log 2>&1
Restart=no
RestartSec=10

[Install]
WantedBy=multi-user.target

$ sudo systemctl status test.service
● test.service - Мой тестовый сервис
   Loaded: loaded (/lib/systemd/system/test.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Sun 2021-07-04 12:22:31 +06; 2s ago
  Process: 24128 ExecStartPre=/bin/echo OPTS=$OPTS_COMMON>/tmp/run.log (code=exited, status=127)
 Main PID: 21783 (code=exited, status=1/FAILURE)

spider@spider ~/src/test $ whereis echo
echo: /bin/echo