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Railway•2y ago

Datadog agent + app stages in same dockerfile

Hi ! Following @Rafal 's suggestion in thread #Recommended way of connecting datadog-agent I tried running a datadog agent and an app in the same Dockerfile (two stages since we have FROM datadog/agent:7 for the agent and FROM node:16.6.1-alpine3.14 for the app). Locally it works perfectly fine, both stages are working. But on railway, only the second one is ran : the app one. The datadog agent stage is discarded, any idea why ? Here is the dockerfile :

FROM datadog/agent:7

ENV DD_APM_ENABLED=true
ENV NON_LOCAL_TRAFFIC=true
ENV DD_APM_NON_LOCAL_TRAFFIC=true
ENV DD_DOGSTATSD_NON_LOCAL_TRAFFIC=true
ENV DD_HOSTNAME=test
ENV DD_TRACE_STARTUP_LOGS=true 
ENV DD_SITE=datadoghq.eu

ARG DD_API_KEY
ENV DD_API_KEY=$DD_API_KEY

FROM node:16.6.1-alpine3.14

# Copy your application files to the Docker container
COPY . /app
WORKDIR /app

# Install your application's dependencies
RUN npm install

# Set the Docker container to run your application when it starts
CMD ["node", "index.js"]

EXPOSE 3000

FROM datadog/agent:7

ENV DD_APM_ENABLED=true
ENV NON_LOCAL_TRAFFIC=true
ENV DD_APM_NON_LOCAL_TRAFFIC=true
ENV DD_DOGSTATSD_NON_LOCAL_TRAFFIC=true
ENV DD_HOSTNAME=test
ENV DD_TRACE_STARTUP_LOGS=true 
ENV DD_SITE=datadoghq.eu

ARG DD_API_KEY
ENV DD_API_KEY=$DD_API_KEY

FROM node:16.6.1-alpine3.14

# Copy your application files to the Docker container
COPY . /app
WORKDIR /app

# Install your application's dependencies
RUN npm install

# Set the Docker container to run your application when it starts
CMD ["node", "index.js"]

EXPOSE 3000

Solution:

try this again but use service datadog-agent start instead of the systemctl thing

Jump to solution

56 Replies

Percy•2y ago

Project ID: 6bd9c9dd-822c-457b-a37e-0abf3c4579fb

Anthony 🦅OP•2y ago

6bd9c9dd-822c-457b-a37e-0abf3c4579fb

luna•2y ago

Doesnt using FROM start a fresh layer without anything from the one before? 🤔 From the docker docs.

With multi-stage builds, you use multiple FROM statements in your Dockerfile. Each FROM instruction can use a different base, and each of them begins a new stage of the build. You can selectively copy artifacts from one stage to another, leaving behind everything you don’t want in the final image. To show how this works, you can adapt the Dockerfile from the previous section to use multi-stage builds.

Anthony 🦅OP•2y ago

Yes I think so, and that's not a problem. I tried this locally and it worked with this exact dockerfile. But it seems like on railway the first stage is simply not launched, whereas locally it is.

luna•2y ago

Are you sure on that? Ive never seen a dockerfile act the way you're describing.

Anthony 🦅OP•2y ago

I think you're right, I might have misunderstood the problem

Brody•2y ago

im with luna on this, anything that you install or launch in the previous FROM derivative is not carried over to the next FROM unless you explicitly copy it over

Anthony 🦅OP•2y ago

Ok good thing we got that out of the way, thank you. I removed the app's stage and only kept the datadog one here is the docker file :

FROM datadog/agent:7

ENV DD_APM_ENABLED=true
ENV NON_LOCAL_TRAFFIC=true
ENV DD_APM_NON_LOCAL_TRAFFIC=true
ENV DD_DOGSTATSD_NON_LOCAL_TRAFFIC=true
ENV DD_HOSTNAME=test-mother-production.up.railway.app
ENV DD_LOGS_ENABLED=true

ARG DD_API_KEY

FROM datadog/agent:7

ENV DD_APM_ENABLED=true
ENV NON_LOCAL_TRAFFIC=true
ENV DD_APM_NON_LOCAL_TRAFFIC=true
ENV DD_DOGSTATSD_NON_LOCAL_TRAFFIC=true
ENV DD_HOSTNAME=test-mother-production.up.railway.app
ENV DD_LOGS_ENABLED=true

ARG DD_API_KEY

The agent is running fine but I don't see any activity of the container in my datadog dashboard, why is that ? When running this exact one locally I see the container on my dashboard.

luna•2y ago

When running it locally are you passing in the docker socket by chance?

Anthony 🦅OP•2y ago

What do you mean ?

luna•2y ago

Whatre you actually trying todo? I have a feeling you may not need the agent at all for this.

Anthony 🦅OP•2y ago

So I have this app :

const tracer = require("dd-trace").init();
const express = require("express");
const app = express();

app.get("/", (req, res) => {
  res.send("Hello World!");
});

app.listen(3000, () => {
  console.log("Example app listening on port 3000!");
});

const tracer = require("dd-trace").init();
const express = require("express");
const app = express();

app.get("/", (req, res) => {
  res.send("Hello World!");
});

app.listen(3000, () => {
  console.log("Example app listening on port 3000!");
});

And the docker agent container running on my computer. This lets me monitor the app. Now I'm only trying to run the container on railway without the app to see if I see it on the datadog dashboard

luna•2y ago

I see

Anthony 🦅OP•2y ago

Just like I see it when i simply run the container locally

luna•2y ago

Okay so you will need the agent just inside the container with your node app. Or 🤔 https://railway.app/template/78cMS9

Anthony 🦅OP•2y ago

theoretically this is what I want The thing is before doing that, I'm trying to understand why does the container running right now on railway isn't detected by my dashboard I have an idea, is it possible to edit the docker run command used to run the container on railway ?

Brody•2y ago

no

luna•2y ago

You might need to use their alpine container and then install node on that.

Brody•2y ago

or install the agent in the node image with data dog's install script

Anthony 🦅OP•2y ago

Local

Anthony 🦅OP•2y ago

Railway

Anthony 🦅OP•2y ago

I see some differences in the logs do you have any idea why that's happening ? Could you give me more details about how to do that ?

Brody•2y ago

UNTESTED think of this as a pseudo dockerfile

FROM node:16.6.1

ENV DD_INSTALL_ONLY=1
ENV DD_SITE=datadoghq.com

RUN bash -c "$(curl -L https://s3.amazonaws.com/dd-agent/scripts/install_script_agent7.sh)"

WORKDIR /app

# Copy your application files to the Docker container
COPY . .

# Install your application's dependencies
RUN npm install

# Set the Docker container to run your application when it starts
CMD systemctl restart datadog-agent.service && node index.js

FROM node:16.6.1

ENV DD_INSTALL_ONLY=1
ENV DD_SITE=datadoghq.com

RUN bash -c "$(curl -L https://s3.amazonaws.com/dd-agent/scripts/install_script_agent7.sh)"

WORKDIR /app

# Copy your application files to the Docker container
COPY . .

# Install your application's dependencies
RUN npm install

# Set the Docker container to run your application when it starts
CMD systemctl restart datadog-agent.service && node index.js

luna•2y ago

https://github.com/gdraheim/docker-systemctl-replacement#problems-with-systemd-in-docker

GitHub

GitHub - gdraheim/docker-systemctl-replacement: docker systemctl re...

docker systemctl replacement - allows to deploy to systemd-controlled containers without starting an actual systemd daemon (e.g. centos7, ubuntu16) - GitHub - gdraheim/docker-systemctl-replacement...

Brody•2y ago

🤷

Anthony 🦅OP•2y ago

That's clever let me try that thanks

Brody•2y ago

it likely wont work

Anthony 🦅OP•2y ago

due to that ?

Brody•2y ago

I don't know what that link is complaining about have you set your DD_API_KEY in the service variables

Anthony 🦅OP•2y ago

Yes I did "/bin/sh: 1: systemctl: not found" :/

Brody•2y ago

well luna did warn us lol and i did say it would likely not work

Anthony 🦅OP•2y ago

I'mma try her approach So the app runs : Example app listening on port 3000! But the agent doesn't (at least I don't have anything on the DD dashboard). i'm in local is there a way to see the logs of the agent ?

FROM node:16.6.1

ENV DD_INSTALL_ONLY=1
ENV DD_APM_ENABLED=true
ENV NON_LOCAL_TRAFFIC=true
ENV DD_APM_NON_LOCAL_TRAFFIC=true
ENV DD_DOGSTATSD_NON_LOCAL_TRAFFIC=true
ENV DD_HOSTNAME=test-mother-production.up.railway.app
ENV DD_LOGS_ENABLED=true

ARG DD_API_KEY
ENV DD_API_KEY=${DD_API_KEY}

ARG DD_SITE
ENV DD_SITE=${DD_SITE}

# Download the systemctl replacement script
RUN apt-get update && apt-get install -y wget python && rm -rf /var/lib/apt/lists/* 
RUN wget https://raw.githubusercontent.com/gdraheim/docker-systemctl-replacement/master/files/docker/systemctl.py -O /usr/bin/systemctl
RUN chmod +x /usr/bin/systemctl

RUN bash -c "$(curl -L https://s3.amazonaws.com/dd-agent/scripts/install_script_agent7.sh)"

WORKDIR /app

# Copy your application files to the Docker container
COPY . .

# Install your application's dependencies
RUN npm install

# Set the Docker container to run your application when it starts
CMD systemctl restart datadog-agent.service && node index.js

EXPOSE 3000

FROM node:16.6.1

ENV DD_INSTALL_ONLY=1
ENV DD_APM_ENABLED=true
ENV NON_LOCAL_TRAFFIC=true
ENV DD_APM_NON_LOCAL_TRAFFIC=true
ENV DD_DOGSTATSD_NON_LOCAL_TRAFFIC=true
ENV DD_HOSTNAME=test-mother-production.up.railway.app
ENV DD_LOGS_ENABLED=true

ARG DD_API_KEY
ENV DD_API_KEY=${DD_API_KEY}

ARG DD_SITE
ENV DD_SITE=${DD_SITE}

# Download the systemctl replacement script
RUN apt-get update && apt-get install -y wget python && rm -rf /var/lib/apt/lists/* 
RUN wget https://raw.githubusercontent.com/gdraheim/docker-systemctl-replacement/master/files/docker/systemctl.py -O /usr/bin/systemctl
RUN chmod +x /usr/bin/systemctl

RUN bash -c "$(curl -L https://s3.amazonaws.com/dd-agent/scripts/install_script_agent7.sh)"

WORKDIR /app

# Copy your application files to the Docker container
COPY . .

# Install your application's dependencies
RUN npm install

# Set the Docker container to run your application when it starts
CMD systemctl restart datadog-agent.service && node index.js

EXPOSE 3000

here is the dockerfile

Brody•2y ago

what do the deployment logs look like

Anthony 🦅OP•2y ago

Brody•2y ago

the railway deployment logs

Anthony 🦅OP•2y ago

I didn't deploy on railway Let me deploy that config

Brody•2y ago

where did you deploy it

Anthony 🦅OP•2y ago

that's local the container on my pc

Brody•2y ago

well get to deploying lol

Anthony 🦅OP•2y ago

Anthony 🦅OP•2y ago

Not surprising

Brody•2y ago

doesn't look like the agent was started

Solution

Brody•2y ago

try this again but use service datadog-agent start instead of the systemctl thing

Anthony 🦅OP•2y ago

Anthony 🦅OP•2y ago

i think it's working https://test-mother-production.up.railway.app/ but can't access the app url

Anthony 🦅OP•2y ago

Anthony 🦅OP•2y ago

+ it worked locally

Brody•2y ago

is it working because you used service datadog-agent start

Anthony 🦅OP•2y ago

Yes I think so Thanks for that + it simplifies the dockerfile

Brody•2y ago

what web framework are you using

Anthony 🦅OP•2y ago

express js

Brody•2y ago

read this please https://docs.railway.app/troubleshoot/fixing-common-errors

Anthony 🦅OP•2y ago

It works !

Brody•2y ago

does datadog work too? i know the agent starts, but do logs show in the datadog site

Anthony 🦅OP•2y ago

Yes i have the logs too Thanks a lot @Brody @ImLunaHey

Brody•2y ago

no problem!

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