fields's questions

It seems that docker build won't overwrite a file it has previously copied. I have a dockerfile with several copy instructions, and files touched in earlier COPY directives don't get overwritten by later ones.

A simplified example (although it also happens if the first copy is an entire directory that happens to contain the file in question):

COPY docker/config/file1.yml $BASE/config/thatfile.yml
COPY docker/config/file2.yml $BASE/config/thatfile.yml

After building this, $BASE/config/thatfile.yml contains the contents of file1.yml. Is there a way to get it to contain the contents of file2.yml?

My primary use case here is copying a whole folder of config files, and then replacing select config files for specific builds.

If you use a stack like ELK or datadog for collecting server-side logs and events, how do you integrate mobile-side metrics? Is there any way to get these out of crashlytics directly, or does this log aggregation need to be implemented separately?

I have the AMIs I want to allow tagged with the "type" tag.

Here's the policy I tried:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "ec2:RunInstances",
        "ec2:StartInstances"
      ],
      "Condition": {
        "StringEquals": {
          "ec2:ResourceTag/type": "permitted_amis"
        }
      },
      "Resource": [
        "*"
      ]
    },
    {
      "Effect": "Allow",
      "Action": [
        "ec2:DescribeInstances",
        "ec2:CreateTags"
      ],
      "Resource": [
        "*"
      ]
    }
  ]
}

When I tried to launch an instance from one of those AMIs, I got permission denied.

I have nagios up and running with nrpe, but I'm relatively new to configuring it myself.

Is there any way to get the raw numbers for the checks, instead of just ok/not ok?

For example, if I want to monitor memory usage of a host over a process that runs for a few hours and see how it fluctuates, can nagios do that, or will it only tell me if it trips some threshold?

I want to use DHCP to pick up the network configuration information including DNS, but still assign a static IP address.

On OS X, this is "Using DHCP with manual address", but I see no similar configuration option for ubuntu in the GUI, and I can't find any information about how to configure /etc/network/interfaces to do that.

I have a 12TB enclosure that's filled with data (ext3). I'd like to make a copy of it, spanned across individual 3TB disks, each of which is readable on its own (no RAID or bonding). Ideally, I'd like this process to spit out some index of which files are on which disk, but that's not strictly necessary. The end result must be readable files on the disk in the original directory structure, not an archive file. Splitting directories (duplicating the directory structure) across volumes is fine.

The 3TB disks are not all mounted at the same time (and not able to be), so I need something that will let me pause the copying to switch disks. I strongly prefer a solution that doesn't require me to figure out which files go on which disk or keep track of what's been copied.

Is there an existing package that will do this?

I have a backup procedure for ec2 instances with lvm spanned volumes that does the following:

1) ssh to the box as root using an ssh forced command to dmsetup suspend the spanned volume. 2) take an ebs snapshot of the volumes 3) ssh to the box as root using an ssh forced command to dmsetup resume the spanned volume.

This has been working fine for a while, but last night something went wrong. It appears that the volume was suspended and never came back to the active state. I could ssh into the instance, but very few commands worked (ls did, top did, ps did not). I could run dmsetup info to see that it was suspended, but attempts to run dmsetup resume did nothing. I eventually rebooted, and it forced a disk check on that volume, which will take a very long time. I've restored from a previous snapshot instead.

What might have gone wrong here, and are there any steps I can take to prevent this from happening in the future?

If you try to append to a file with no write permissions (say, the /etc/sudoers file which is is owned by root and has 0440 permissions), if you're the actual root user, this works. However, if you're another user using sudo, you get a permission denied error.

Why is this? It not because of the ownership of the file - it doesn't work with files owned by the normal user either. The real root user seems to have more permissions than are granted with sudo. What's the rationale for this? Is there a way to grant this permission to users using sudo?

Fetchmail only has the option to delete mail from the server or not. Is there something that exists that does basically exactly what fetchmail does, except which also supports the option to only delete mail older than some time period?

Launching a screen session with a background process using -d -m causes the screen session to terminate when the process exits.

Is there any way to get the screen session to stick around after the process exits, but still launch it without any user interaction?