Here's a preview from my zine, How Containers Work! If you want to see more comics like this, sign up for my saturday comics newsletter or browse more comics!
read the transcript!
containers often get their own IP address
wordpress container 1: I’m running WordPress at 172.17.2.3:8080!
wordpress container 2: I’m using 172.17.0.49:8080!
containers use private IP addresses
These are reserved for private networks (RFC 1918).
This is because they’re not directly on the public internet.
for a packet to get to the right place, it needs a route
packet 172.16.2.3: hi! I’m here!
router, represented by a box with a nonplussed expression: I don’t have any entry
matching 172.16.2.3 in my route table, sorry!
inside the same computer, you’ll have the right routes
same computer:
$ curl 172.16.2.3:8080
<html>....
different computer:
$ curl 172.16.2.3:8080
.... no reply ....
distributing the right routes is complicated
box with a smiley face: a new container started, 10.2.73.4 should go to X computer now
route table, also represented by a box with a smiley face, thinking: wow these things change a lot
cloud providers have systems to make container IPs work
In AWS, this is called an “elastic network interface” route table
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