CODEWITHSUNDEEP
c++dockerredis
Jonathan Tuzman
Jonathan Tuzman

Reputation: 13262

Connecting to Redis in Docker from Redis++

In my docker-compose file, redis is exposed at 6379, and reader is a gcc container.

  reader:
    build:
      context: ./reader-manager
      dockerfile: reader_manager.dockerfile
    volumes: 
      - './reader-manager:/avn/reader-manager'
    depends_on: 
      - redis    

  redis:
    image: redis
    ports:
      - 6379:6379

In my C++ code, I am having trouble connecting to the redis instance:

auto redis = Redis("tcp://127.0.0.1:6379");
redis.set("key", "val");

This results in

Failed to connect to Redis: Connection refused

Other containers in the environment (like flask) are connecting fine to redis, although they use a url starting with redis:// but when I try in my C++ code:

auto redis = Redis("redis://127.0.0.1:6379");
redis.set("key", "val");

I get

invalid URI: invalid type.

I've also tried unix:// with the result:

Failed to connect to Redis: No such file or directory

Not sure if it matters, but here's the reader dockerfile

FROM gcc:latest

RUN apt-get update -y
RUN apt-get install cmake -y

# install/compile hiredis
WORKDIR /avn
RUN git clone https://github.com/redis/hiredis.git
WORKDIR /avn/hiredis
RUN make
RUN make install

# install/compile redis-plus-plus
WORKDIR /avn
RUN git clone https://github.com/sewenew/redis-plus-plus.git
WORKDIR /avn/redis-plus-plus
RUN mkdir compile
WORKDIR /avn/redis-plus-plus/compile
RUN cmake -DCMAKE_BUILD_TYPE=Release -DREDIS_PLUS_PLUS_BUILD_TEST=OFF -DREDIS_PLUS_PLUS_CXX_STANDARD=17 ..
RUN make
RUN make install

# compile and run the program
WORKDIR /avn/reader-manager
CMD make && ../../bin/main

Upvotes: 0

Views: 801

Answers (1)

eerorika
eerorika

Reputation: 238281

127.0.0.1 is a loop-back address. A loop-back address connects back to the container that makes the connection. If the C++ program runs in the reader container, then redis isn't running in the same container. You need to connect to the redis container:

auto redis = Redis("tcp://redis:6379");

I wouldn't recommend hard-coding it in the executable though. Make it configurable.

Upvotes: 1

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