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https://github.com/batiati/dateoffset
Modifies the system time for a single application or container.
https://github.com/batiati/dateoffset
datetime docker intercept-calls jemalloc libfaketime mssql mssqlserver
Last synced: about 1 month ago
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Modifies the system time for a single application or container.
- Host: GitHub
- URL: https://github.com/batiati/dateoffset
- Owner: batiati
- License: unlicense
- Created: 2021-07-07T23:12:42.000Z (over 3 years ago)
- Default Branch: master
- Last Pushed: 2021-07-08T12:28:08.000Z (over 3 years ago)
- Last Synced: 2024-10-12T07:21:06.768Z (2 months ago)
- Topics: datetime, docker, intercept-calls, jemalloc, libfaketime, mssql, mssqlserver
- Language: C
- Homepage:
- Size: 2.93 KB
- Stars: 4
- Watchers: 3
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Lib dateoffset
### Modifies the system time for a single application or container through Linux syscall
## 1. What is it
_Lib dateoffset_ provides a very simple way to run a single application or container with a different date, without changing the system clock.
It's useful for testing and debugging code that are time-dependant, like databases, certificates, and all sort of business logic that involves dates.
## 2. Motivation
If you are looking for a portable and full featured solution, you might opt for the excellent [libfaketime](https://github.com/wolfcw/libfaketime).
Unfortunately the way [libfaketime](https://github.com/wolfcw/libfaketime) works [clash with some applications](https://github.com/wolfcw/libfaketime/issues/130) using [jemalloc](http://jemalloc.net/) as memory allocator, which apperas to be the case of [Microsoft SQL Server for Linux](https://hub.docker.com/_/microsoft-mssql-server) and many other applications.
_Lib dateoffset_ solves it by eliminating memory allocations caused by `dlsym` and directly calls Linux `clock_gettime` syscall.
I strongly suggest you to try [libfaketime](https://github.com/wolfcw/libfaketime) first before using this one.
## 3. Usage
Just like [libfaketime](https://github.com/wolfcw/libfaketime), the basic way of running any command/program with _Lib dateoffset_ is getting it loaded by system's linker using the environment variable `LD_PRELOAD`.
However, unlike [libfaketime](https://github.com/wolfcw/libfaketime), _Lib dateoffset_ is much more limitted and has just one way to define the date, through the environment variable `DATE_OFFSET` with the start date in epoch format (seconds since 1970-01-01 00:00:00 UTC). You can use the command [date](https://man7.org/linux/man-pages/man1/date.1.html) to convert a date in format `yyyy-MM-dd` to seconds.
Examples:
a) Setting the environment variables
```bash
export LD_PRELOAD=/path/to/dateoffset.so
export DATE_OFFSET=$(date -d "2012/12/21 12:00:00" '+%s')
# (now run any command you want) #
```
b) Or it can be done by specifying it on the command line itself:
```bash
LD_PRELOAD=/path/to/dateoffset.so \
DATE_OFFSET=$(date -d "2019-10-30 00:00:00" '+%s') \
# your_command_here #
```
c) Changing just the date, but keeping the time unchanged
```bash
LD_PRELOAD=/path/to/dateoffset.so \
DATE_OFFSET=$(($(date -d "2016-10-12" '+%s') + ($(date '+%s') % (24*60*60)))) \
# your_command_here #
```
d) Dockerfile
```Dockerfile
ENV LD_PRELOAD=/path/to/dateoffset.so
ENV DATE_OFFSET=2090-07-04
ENTRYPOINT ["/my-app"]
```
## License
* This project is a free and unencumbered software released into the public domain. Plese visit [unlicense.org](https://unlicense.org/) for more details.