How can I install package from private repository using docker

I am installing a package from my private repository. I am able to install it using:
npm i -S git+https://oauth2:[email protected]/mygroup/acl-api.git

I am using docker container but while installation process I am getting an error:

npm ERR! path git
npm ERR! code ENOENT
npm ERR! errno ENOENT
npm ERR! syscall spawn git
npm ERR! enoent Error while executing:
npm ERR! enoent undefined ls-remote -h -t https://oauth2:[email protected]/mygroup/acl-api.git
npm ERR! enoent
npm ERR! enoent
npm ERR! enoent spawn git ENOENT
npm ERR! enoent This is related to npm not being able to find a file.
npm ERR! enoent

How can I solve it?

My docker file:

FROM node:alpine

COPY package.json package.json
COPY src src
COPY .babelrc .babelrc

RUN npm install  
RUN npm run gitlab-build

RUN ls
EXPOSE 8080
CMD ["npm", "run", "docker-start"]

Source: StackOverflow